Are these new fabricated housings restricted to race cars only? Absolutely not. There are plenty of applications, race cars and otherwise (including your street-driven Chevy) that can make use of similar housings. Given the "trickle-down effect" of motorsports, several manufacturers recognized the fact that many of these cars had plenty of heat under the hood, too. And much like their professional racing counterparts, they too were twisting, bending, and otherwise mangling rearend housings. As a result, there are countless Bow-Tie applications that can make use of a contemporary sheetmetal axlehousing. It should be noted, however, that there are also plenty of cases where it just makes sense to use a something like a modified 12-bolt. In some cars, you may not require the beef of a completely braced housing. And in some applications, it simply may be more economical to use a conventionally reworked Chevy housing (which, by the way, can prove plenty stout for performance use).
Does the chassis configuration of your Chevy restrict the use of sheetmetal housings? Several of the manufacturers can build a sheetmetal housing to any width you desire, while others are geared toward narrowed assemblies. In other words, you don't have to have a full tube frame Pro Stock chassis or a Top Fuel car to enjoy the benefits of the fabricated housing. A good example of this is the series of "Fab 9" housings offered by Chassisworks:
Chassisworks offers the Fab 9 in at least six different incarnations. Chassisworks manufactures "bolt-in" housings for First-Generation GM A-bodies ('64-'72 Chevelles), '67-'69 Camaros (and Firebirds), '62-'67 Chevy IIs and '78-'88 A- and G-bodies (Malibus, Monte Carlos, etc.). These housings are engineered as direct replacements and maintain original dimensions and suspension mounting points. In addition to these bolt-in assemblies, Chassisworks also offers the Fab 9 in a basic format which includes a fully welded center section, axletubes installed, any style of machined housing end (housing ends are included with all Fab 9 housings), a filler cap and drain plug installed, along with all applicable hardware. Finally, the same housing is available with a back brace, an axle vent tube installed, and Chassisworks' Eliminator II four-link brackets. All hardware is installed and welded to fit the dimensions of a given chassis.
How is a typical sheetmetal housing constructed? Using a Jerry Bickel housing as an example, each housing is constructed on a purpose-built, machine-ground surface plate. This keeps the housing dimensionally true during fabrication (under construction, the housing is indexed to the special surface plate fixture which orients the case to the bearing centers). The axletubes (which are 3.250-inch-diameter, 0.250-inch wall 4130 chrome moly steel) run inboard and attach to an inner bulkhead inside the housing center. The faceplate and backing plate are laser-cut from 4130 chrome moly steel plate, and are designed to support the folded chrome moly sheetmetal case and brace assembly. A set of 360-degree four-link brackets is welded to the tubes and also support the case assembly, which effectively adds four more bulkhead supports. Jerry Bickel also points out that his fabricated housing is available in a variety of four-link centerline dimensions from 17.00 inches (minimum) to 21.00 inches (maximum). These housings are equipped with wishbone (centering device) brackets, shock mounts, wheelie bar mounts, tie-down hooks, a large-diameter fill/inspection cap, a housing vent, and a drain plug. All gasket surfaces are machined, and the housing is align-bored after all welding is complete-again using the index fixture to ensure that the housing is true. Finally, the housing bearing ends are installed using a special, dimensionally accurate fixture manufactured by Mark Williams Enterprises. By using this fixture, Bickel is assured vertical and horizontal alignment with zero tolerance.