The 1970 Chevelle SS is not only one of the most sought-after cars in the world, but it's also one of the most faked and cloned as well. There is nothing worse than hearing about a fellow car enthusiast purchasing a bogus car and becoming a victim of fraud. The purpose of this article is to identify some basic features of the 1970 Chevelle SS, which can help the average enthusiast detect fabricated features and lower the risk of making a bad purchase.
Titles or terms such as True SS, Numbers Matching, and Correct Original are frequently used as selling points for a 1970 Chevelle SS. This can be very misleading, as these terms are often used loosely—and even abused. With any assertion, there must be sufficient facts or documents to support the claim in order for it to be deemed accurate. We offer up some technical insight on these terms as well as the supporting evidence that should be present to back them up.
Proving the authenticity of a 1970 Chevelle SS can be a very daunting task without the existence of sufficient documentation, such as the original assembly plant "buildsheet" or the vehicle's original warranty card (Protect-o-Plate). The vast majority of 1970 SS Chevelles in the "For Sale" market do not possess either of these documents; therefore, we will mainly focus on the physical characteristics of the 1970 Chevelle SS rather than the documents themselves.
When documentation is no longer available, a thorough inspection of the car's driveline components and body is imperative. The main purpose of this inspection is to check for the original existence of mandatory components that were standard equipment with the RPO Z25 SS396 and Z15 SS454 options. It must be noted that options such as front power disc brakes; SS-style, round-gauge dash; 12-bolt rear end; RPO M40 (if originally equipped with automatic transmission); and RPO F41 suspension do not prove a 1970 Chevelle to be an original SS model, but evidence to support that all of these options were originally present is mandatory. The RPO M40 automatic transmission was the only automatic available for both RPO Z25 and Z15 packages, hence the reason for including it in this list.
The following photos will assist in providing a better understanding of the physical traits of a 1970 Chevelle SS. A thorough inspection is essential to drawing well-informed conclusions based on your findings, and it will also enable you to make excellent purchasing decisions.
A couple of fully documented 1970 SS396 Chevelles. These cars have only a single repaint, all original body panels, and are unrestored. Both cars also retain their original assembly-plant buildsheet and Protect-o-Plate.
1970 Chevelle SS454 LS6 M22 4.10 Positraction. Cranberry-red with code-788 red bucket-seat interior.
1970 Chevelle Malibu original-paint survivor, featuring a 307ci engine and automatic transmission. Classic white, with gold bench-seat interior.
Examining the firewall of a 1970 Chevelle can be very helpful in determining the existence of certain original assembly-line provisions. This information can be compared with the floorpan as well to draw additional conclusions. The provisions for these options are generally located in the areas depicted in the Exhibit 1 photo above. A 1970 Chevelle cannot be proven to be an SS model by examining the firewall alone, but it can provide evidence to support the likelihood of certain RPO options that were originally present.
A 1970 Chevelle cannot be proven to be a SS model by examining the VIN (Vehicle Identification Number), nor by examining the Body by Fisher (cowl tag) plate, unless the car was assembled at the Oshawa Canada Plant, which was the only plant to list the RPO codes directly on the cowl tag. Notice the existence of RPO Z25 (SS396) on the tag pictured above.
The general consensus among Chevelle enthusiasts is that the Leeds Plant in Kansas City, Missouri, identified the cars that were to be assembled with SS equipment with the infamous "L" designation on the cowl tag. But it also must be noted that a few rare cases of SS models have surfaced without the "L" designation. An example of the "L" designation on the cowl tag is pictured above.
The most prominent physical trait of a 1970 Chevelle that can prove with absolute certainty that it was originally an SS model is the existence of evidence showing that any RPO L34, L78, LS5, or LS6 engines was the original engine. 1970 Chevelles assembled with the RPO Z25 SS396 option were assembled with 3969854 casting-number engine blocks. The casting number and the date it was cast was molded into the rear of the engine block just above the bellhousing area.
The big-block Chevrolet engine-assembly plant located in Tonawanda, New York, used a specific dating system for casting the 1970 Chevelle SS: a letter of the alphabet indicating the month, followed by the day of the month, and a "9" for the year 1969 or a "70" for 1970. The photo above shows a casting date of I 12 9. This would indicate the following: I = September; 12 = 12th day; and 9 = 1969. (Note: Dates that were cast into a mold used the letter "I", items dated using a stamping method skipped the letter "I" and therefore M would equal December.)
The date the engine was assembled, the cubic-inch displacement, and the transmission designation was stamped on the front right-hand side of the engine directly in front of the right-side cylinder head. The stamping T0916CTW indicates the following: T= Tonawanda, New York, engine plant; 0916 = September 16 assembly date; and CTW indicating RPO L34 engine and RPO M40 transmission. Notice the block was cast on the 12th and built on the 16th. It is common for engines to be either cast and built on the same day or more than four months later. The 10A100454 stamp is what is known as a VIN sequence number. This stamp was done at the final assembly plant and not at the engine plant. It was for warranty purposes and both the front engine pad and the vertical pad directly above the oil filter were used for this stamp. The final assembly plant of the car in question will determine which of these two locations it will most likely appear. The stamp 10A100454 indicates the following: 1=Chevrolet Motor Division; 0=1970; A= Atlanta, Georgia, assembly plant; 100454 is the last six digits of the vehicle's VIN. This is the stamp that is used to signify "Numbers Matching" and is very important. In order for a 1970 Chevelle SS to be appropriately deemed Numbers Matching, it must meet all of the following requirements: the casting number of the engine block must be correct for the car in question; the casting date and assembly date of engine must precede the assembly date of the car generally by two weeks or more (this is to allow for shipping from Tonawanda, New York, to the various assembly plants); the VIN sequence must match the assembly plant's procedures with the location of the stamp as well as the appropriate font for the assembly plant in question; and the last six digits of the VIN sequence must match the last six digits of the car's VIN.
The engine-block casting number used in 1970 Chevelle SS featuring the RPO Z15 SS454 option was 3963512.
As explained previously, the casting date pictured indicates J 14 9, which translates to October 14, 1969.
The assembly date reads T0129CRV, which indicates Tonawanda, New York; January 29, 1970; and CRV for RPO LS6 and M22 manual transmission. Notice the casting date precedes the assembly date by more than three months. This indicates the engine sat around waiting to be assembled by this length of time. Also, notice the larger font and the upside-down stamping. This was normal procedure at the Kansas City, Missouri, plant.
The casting-number main case for 1970 Chevelle SS with RPO M20, M21, and M22 manual transmission was 3925661. A few early-production cars were also equipped with 3925660 casting-number main case. The M22 carried 26-input and 32-output splines, while the M20 and M21 are known to carry 10-input and 27-output splines.
An excellent example of the infamous RPO M22 "Rock Crusher" manual transmission. The date-code stamp P0C23C indicates P=Muncie; 0=1970; C=March; 23=23rd day; and C=M22. The last letter of the date code indicates the RPO transmission: A= M20 and B=M21. It is also very important to check for the assembly-plant VIN sequence stamping, which will be in close proximity to the date stamp or on top of the transmission. Engines and transmissions were the only driveline components that received this stamp for warranty purposes.
Take notice of the seven-bolt side cover and shifter attaching arms that are attached with a bolt instead of a stud and nut used in earlier years. The part-number tag indicates 3978766 WO, which stands for M22. A M20 transmission part-number tag would be 3952659 WB, and M21 used part numbers 3968011WL and 3968012WL.
RPO Z25 SS396 and Z15 SS454 were only available with RPO M40 Turbo-Hydromantic 400 when equipped with automatic transmission. The photo above indicates a casting date of 12-69 (December 1969). This date is located on top and the rear of the transmission just before the tailshaft attachment bolts.
The identification tag is attached to the passenger side of the transmission above the pan rail. This tag indicated the model year, engine type, assembly date, and trans serial number. The tag pictured indicates 394, which is January 29, 1970 assembly date (394th day from January 1, 1969); 70= 1970; CY= special shift point (RPO LS6); 1732= transmission serial number. RPO LS5 received code CS and a few were known to be code CR. RPO L34 received code CF and RPO L78 received code CW. The special, high-performance RPO LS6 (CY code) and RPO L78 (CW code) TH400 were also equipped with a heavy-duty six-bolt torque converter.
The VIN sequence number on this transmission is 10K192328. This stamp is located on the driver's side just above the pan rail. Inspect this stamp to determine if the transmission is original to the car.
The photo above is a casting date of a 12-bolt rear-axle assembly. The casting date K 21 9 is similar to dating system used on engine blocks: K=November; 21=21st day; and 9=1969. This stamp will be on the back-side of the rear-axle assembly directly to the lower right of the differential cover.
A prefix code that designated gear ratio and determined whether the rear-axle assembly was equipped with a limited-slip or an open-style carrier was stamped on the righthand-side axletube facing forward. This was followed by a stamp that indicated the build date of the rear-axle assembly, a letter that designated the assembly plant of the rear-axle assembly, and a number indicating which workers assembled the item from either first or second shift. The photo above is an example of a rear-axle assembly only offered with the RPO Z15 SS454 option indicating a CRV 1128B2 stamp. This indicates the following: CRV= 3.31 gear ratio and Positraction (RPO Z15 only); 11=November; 28=28th day; B=Buffalo, New York, rear-axle assembly plant; 2=2nd shift. The build date of the rear-axle assembly generally precedes the build date of the car by at least two weeks to allow for shipping from the rear-axle assembly plant to the various final-assembly plants. Notice the slight stair step in the CRV and the font, which is correct. Careful examination of authentic rear-axle stamps is important as they are sometimes bogus.
RPO F41 performance suspension was standard equipment on all SS models. This carried a front stabilizer bar that measured 1.25 inches as opposed to a 1-inch bar for the standard Malibu suspension. A photo of the F41 1.25-inch front stabilizer bar is pictured above.
Standard Malibu suspension with the 1-inch front stabilizer bar.
All 1970 Chevelle SS's were assembled with power-disc front brakes. The correct power-brake booster for a 1970 Chevelle is stamped "9391" on the rear of the top-center tab. This is the correct part number and should be present if the car is still equipped with the original unit.
The stamp on the front of the pad is the date it was assembled and it generally must precede the assembly date of the car. The photo above shows a date of 276, which is the 276th day of 1969. These boosters are usually stamped "Delco Moraine" to identify the assembling manufacturer. This stamp is on the front side and usually upside down. There is a very high probability that a car equipped with the correct "9391" power-brake booster dated within 90 days prior to the build date of the car was equipped with front power-disc brakes from the factory.
Check for the heavy-duty steering shaft. The heavy-duty shaft pictured above has the extra bolt attaching the coupler at the rag-joint area. All SS models will have this heavy-duty steering shaft. The standard Malibu will not have the heavy-duty steering shaft.
Standard Malibu steering shaft.
A 12-bolt rear differential was standard equipment on all SS models. The rear sway bar was part of the RPO F41 suspension package. The casting number for a 1970 Chevelle 12-bolt rear-axle main case is 3969278. The casting number is located on the front-lower side of the axle assembly.
The 10-bolt pictured carried casting number 3969277 and was standard equipment for the 1970 Chevelle Malibu.
Other items to investigate in the RPO F41 suspension were boxed lower-rear control arms and additional frame supports. The boxed control arms will include metal reinforcement plates welded to the bottom of the control arms to provide additional strength. The F41 boxed lower-rear control arm is pictured above.
Standard Malibu suspension without the boxed-in lower control arm.
Additional frame supports included with RPO F41 suspension attach to the center-rear frame support above the rear-axle assembly and to the front attaching point of the lower-rear control arms. It should also be noted that stiffer front and rear coil springs as well as heavy-duty front and rear shocks were also included in the RPO F41 suspension package.
Standard Malibu suspension without the lower control arm to frame support braces.
All SS models carried the round-gauge-type dash assembly pictured above with either standard idiot lights or when the RPO U14 Special Instrumentation option was added. The instrumentation on 1970 models used numerals that had a greenish hue, and 1971 and 1972 models were white. The steering column and gauge area is always black on all SS models. The round-gauge-type SS dash was also used in Malibu models when the RPO U14 option was added.
Standard Malibu sweep-style speedometer dash assembly.
All SS models that were equipped with RPO C60 Air Conditioning were also equipped with RPO V01 Heavy-Duty Cooling. This included a four-core radiator which had a larger driver-side radiator tank. This required a special radiator support with a special tab that was tack-welded in place on the lower driver's side to accommodate the bigger radiator as well as a similar special radiator top plate. An example of this special radiator support is pictured above. A quick glance at any firewall can determine if the car was equipped with RPO C60 Air Conditioning by the opening in the firewall. If so, the car must have this special radiator support to be correct. This radiator support would also be present and mandatory when the RPO LS6 engine option was coupled with RPO ZQ9 4.10 Performance Rear Axle Ratio. RPO V01 Heavy-Duty Cooling was automatically included with the ZQ9 4.10 option for the RPO LS6 engine.
Standard radiator support that accommodated both the two- and three-core radiators.
All SS models featured a black accented grille. Inspect to determine if the grille has been changed or appears to be original.
Standard Malibu featured a gray-colored grille.
The front-bumper parking-light lenses will be clear on all SS models with amber bulbs. More often than not, the cars that were born with clear lenses remained clear. If a car has amber front parking lenses, that should be a red flag.
Standard Malibu amber front parking lens.
All SS models were assembled without the Malibu-style moldings that run fromthe quarter glass area along the top of the doors and fenders. An inspection of the inside of these panels for welded up molding holes will provide helpful information to determine if these body panels were originally installed on a SS model. Also, check for the correct location placement of fender SS emblems. Use a known SS fender as a guide. These are drilled incorrectly very often.
Standard Malibu featuring the molding.
All SS models were assembled with a black-rubber rear bumper pad with an SS insignia. Inspect the bumper pad and bumper bolts for signs of being changed. Original bumper-bolt heads will be a full 1-inch diameter and almost flat. Incorrect bolts will have a much taller crown and are usually smaller than 1.0 inch in diameter.
Standard Malibu featured a solid-chrome rear bumper without the black SS rubber pad.
If you are considering the purchase of a 1970 Chevelle SS, you would be well-advised to do your homework before entering the vintage-car market in search of your dream car. Identifying and becoming the beneficiary of a good buy is extremely dependent upon becoming a knowledgeable buyer who is familiar with the vast level of information briefly discussed in this article, such as engine codes, rear-axle codes, transmission codes, driveline dating systems, correct part numbers, and casting numbers to all driveline components. It's also crucial that this information is stored into your memory, as you must be able to recite it at a moment's notice in order to capitalize on bargains when they present themselves.
The stealthiest of buyers are armed with a lethal amount of knowledge and won't need to research a car on the spot, which is definitely a recipe for missing the boat. The adage "luck is where preparation meets opportunity" definitely applies to the vintage-car market. Indecisiveness, apprehension, and doubt are ugly kin that will fog the sight of your ship when it comes in. Being prepared, experienced, and well informed will let you see your ship in high definition with your name written all over it, and you will most certainly jump on board.