Okay, I have a 1979 ford f-150 2wd with the 400m v8 engine and an automatic transmission, right now my truck has a 1976 c6 transmission in it, and sadly it has finally failed me. So I called my local junk yard, he said he had a 1973 ford drive in with a c6 in it, my question is, will the 73' c6 bolt up to my 79 400m? answers would be greatly appreciated!!

 

Depends what the engine was bolted in the 73. If it was a 429-460 it should be okay, the only difference being a different bearing snout on the torque convertor. If it's a 351C, (did they run these on that model?) than that is very likely to be a small block pattern like the windsors so no go there.
The only other way to be different is if you had the rare as unicorn excrement small block pattern 400. Seemed to have found their way into cars as the story goes and usually had a FMX behind them so realistically this shouldnt be an issue unless someone had a real good play with it before you. Good luck.

 

I believe the 360, and 390s had a different bellhousing also.

 

any auto trans from the 385 series will work with the 400

 

If i remember correctly some tail shaft are different. most are standard. I run 4wds but 2wheel drives believe their was 2 setups? definelty take a tape measure. torque converter a little different. check converter thrust once installed. if pulled to far forward you pull the converter out of the internal pump in tranny, want about 1/8" of play at most at converter.Sometimes have to shim converter to get proper converter set. i believe their is something different on 400 converter compared to 460/429. i'm forgettin stuff but remember it when i'm doing the job. hope i didn't confuse you but got me scratching my head a little myself. haven't had a auto tranny C-6 problem in a long time.