You might see about contacting HevyHauler about an automatic/V8 swap. While the article linked does mention using a Fuller manual, he did end up putting a later Powermatic in it with the 468 big block.
The transmission I used is from a mid eighties topkick it is an Allison 540 4 spd. If I had it to do over it would be a LBZ Duramax and a 6 spd Allison.
