200-4R Conversion

[strick9c10]

I was wondering if anyone has done this conversion...

I have a 79 C-10 that I purchased recently. It has a 425 horse 355 small block between the fenders , but still has the original Saginaw 3 speed transmission in it (the guy never got around to swapping it out).

I want to switch to an automatic, because Muncie & T-10 four speeds are just way too much $$$ in my neck of the woods. I was going to use a TH350 short shaft unit, so I can keep the same driveshaft, but am having a real hard time finding a decent 69-81 unit.

I know the 200-4R tranny is the same length, etc., as a short shaft TH350, but will a 200-4R fit without modifications to the cab, floors, cross-member, etc.

Any ideas, thoughts, etc., are most appreciated & welcome!