The rear crossmember was used in the automatic transmission models. I ran an aluminum case Muncie 4-speed in a dirt track race car for many years without a rear crossmember, and we went from closed throttle to full throttle, 2,500 RPM to 6,000 and back to 2,500 RPM in 2nd. gear 4 times a lap for up to 100 laps. I can't remember ever breaking a trans case except once when the car ended up as the meat in the sandwich in a 3-car pileup, one car on top of the other.
Jerry
