The Stovebolt Site Forums The Shop Area Engine Shop rear end

54 1/2 tons came with a closed driveline (torque tube), so your rear end is not the original. If your 4 speed is a SM420, you want to retain the two piece driveshaft with steady bearing. The SM420 is very short. It's almost impossible to find a one piece driveshaft with slip yoke long enough to to the job. A one piece driveshaft would have been 64" on my truck (which has a Camaro rear end. I went all over looking for a driveshaft that would work, finally used a two piece (the guy who balanced my driveshaft told me I would end up with a two piece - he said a shaft at least 64" long with slip joint was very rare, but I went looking anyway). I think there is are web sites that can help with identifying the rear end; maybe do a search thru the forums?