I used a 13" single disc truck clutch. Full pad on disc not the 6 pucks like the deuces. If my CAT was at 275hp or more, I'd go with a twin disc set up.
Okay...it's been a while, but if I recall correctly...the 3053A's bell is an SAE #3, the CAT had an SAE #2 and the Multifuel had some messed up militarized #1. I had a buddy with a big enough machine machine the step off of the multifuels original plate adapter. I then drew up the three SAE patterns on AutoCad and sent it to another buddy with a plotter big enough to print out the drawing to a 1:1 scale. I located the #3 hole pattern, then center punched the #2 pattern and drilled them. The #3 and #2 patterns are pretty close to each other and I needed to just make a little clearance for the CAT's bell bolts at the outside of the 3053's bell. I also used socket head bolts to reduce the head radius. I called CAT to see if there were adapters out there and they gave me a price of around $400 and the adapter was over and inch thick. Well that wouldn't do! :banghead: Another thing, using a single disc clutch on the CAT made the clutch and t/o bearing about 7/8" farther away from where they were originally in multifuel's clutch arrangement. I took two t/o bearings, machined the face off of one, mached the back off of another with a step so I could press them together then weld the seam. That allowed me to extend the t/o bearing and have the clutch working like normal. without extending the t/o bearing, the clutch rail would not have had enough travel to push the t/o into the pressure plate deep enough. Twin disc would have most likely remedied this, but I didn't feel I needed that extra meat in the clutch.