28 years ago I installed an older Ford Alt on our 800 Diesel. When I say older, I mean the multi-terminal, small frame version (55 amp if I remember right) with an external regulator. It bolted right-up in the proper belt alignment position after reaming out the hole on the alternator body to the size of the generator mounting hole in the lug on the engine block. Biggest problem was modifying the Ford wiring harness to fit the Case layout. I mounted the regulator on the back side of the fuel tank support stamping next to the battery.
Worked so easy and cheap that we've done the same on a 800 gas, a 830 & a 930.