4 Speed Conversion

If the crank doesn't have the right depth to accept the 4-speed input shaft, I've heard of people nipping a little bit off of it to make it work,

Yep,... the previous owner did it on my Barracuda. It's a 400 with a cast crank. There is a roller bearing that presses into the opening in the back of the crank where the nose of the torque converter would normally go. Then you have to cut about 3/4" off the end of the input shaft. Not the best way, but it seems to be working fine in mine. Brewer's sells those bearings too. Pictures shown below of bearing and how it installs

PB5300-1.jpg

Installed.jpg