I have an 84 short bed chevy pickup with a 488" aggressive cam big block. The truck runs 13 inches of lift and 44's. it has a sm 465,an np 205 transfer case, a 14 bolt and dana 60. it is a great rig but for mud running I think I need to swap to an auto. Anybody got any suggestions on which one and who to get if from. I am pretty confident I am going to need a 2000 stall converter. Originally I had planned on putting in an allison five speed but no one can tell me if you can even get a high stall converter for that. I am going to be putting some fairly low gears in it to keep it versatile so I want more gears in the tranny to make up for it.

You really only have one choice for a trans...TH400. I wouldn't put something smaller behind a built big block. If you really need the 4th gear you could go with a 4l80e but you will need to buy a controler for it = $$$. I say go with a TH400 and a doubler for the gearing.