There are a lot of ways to go with this. This is what I did with my 46. I wanted to upgrade the drive train with the idea in the back of my mind to some day drop in a V-8. I have a 55 235. First I found a 56 1/2 ton rear end with 3:56 gears. The center pumpkin will fit right in the 46-54 housing. This way I am using my existing brakes and shocks. I had to weld new spring saddles to the housing because the existing ones were the type thet rotated. Next I found a 53 bellhousing that had the right bolt pattern for the later trans (they changed in late 47) I had to build a mounting bracket that mounts to the new bellhousing to mount the master cyl.and clutch pedal to. Next I used an sm420 4 speed from a 65 1/2 ton this is an open drive line unit. It has a granny low. Next I found a drive line out of a 77 1/2 ton and it was just the right length. NAPA makes a u-joint with two differens sizes that worked perfect to hook it up.. This is just one option.
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Rick cool