Our Formula Firebird (aka Snowball) was originally equipped with a T5 5-speed manual transmission when it rolled off the assembly line. The five-speed Tuned Port Injection (TPI) cars were somewhat unique because the more efficient and light weight five-speed would allow a 5.0 to run about as fast as a 5.7 with an automatic. Sadly GM didn't deem the manual box durable enough to back up the torque of a 350 TPI, so it never found its way into the 350-cube third-gens. Since our Formula's 305 has made way for a healthy LT1 swap, we looked to Monster Transmission in Brooksville, Florida to freshen and upgrade the T5's internals, and Mcleod to safely engage the power with a SFI bell housing, adjustable hydraulic throwout bearing, and RST Twin Disc Clutch. Twin-disc clutches are becoming commonplace on modern performance cars as they dramatically increase holding power without a corresponding increase in pedal effort.
While determining our upgrade path it was impossible to ignore newer and perhaps sexier options like a T56 six-speed or the new Tremec TKO 600. The T56's extra overdrive and out of the box power handling were tempting, but we couldn't justify its 50-pound weight penalty, integration issues, and cost. While good used examples are out there, the costs can still rapidly outrun the overhaul cost on the T5 we already had. The TKO's don't have quite the weight problem of the T56, but are still about 35 pounds heavier and (like the T56) easily outdo the overhaul cost of the T5. Monster Transmission has found a mild rework of the T5 can allow it to handle around 400hp, but horsepower ratings on transmissions are guesses at best because of application and driving style. In our case (open track days), we aren't going to see the shock loads of the drag strip, so we expect this upgraded and modernized T5 should live a long life.
With the Mcleod SFI-approved bell housing bolted up to the T5 we can rev the snot out of our LT1 without worrying about a chunk of flywheel coming up through the floor to ruin the fun.