I am looking to conver my 1978 Ford F100 Flareside with a 300 Inline 6 and 3 speed transmission to a C4. I know I will need the following.
Flexplate
Speedo Cable
Tranny Mount
Vaccum Port for Tranny

My question is will I need a new driveshaft, do they have the same spline, and if I just need to get it cut or lengthened about how much would that cost?

 

if the c4 came out of a truck , grab the drive shaft also ,otherwise a junkyard is a real cool place,bob

 

skip the c-4 and find a small block with a c-6

 

I was considering a 351W, but I would still want a C4, I would just have it built if I go with a V8. I know the C6 is a great trans especially for durability, but I also hear it eats more power than a built up C4, which is just as strong when built up.

 

While the C6 is definately a fine transmission, there is a misconception about the C4 floating around out there, which says that it is the "weak" little brother to the C6. It just ain't so! It is the choice of many serious small block drag racers (and some big block as well). Depending on the year, when properly rebuilt (even using stock parts) the C4 can easily handle 400+ HP. It is much lighter then the C6 and has far less parisitic losses (and the C6 tends to flex under high HP as well). I use a home rebuilt C4 in my race truck without problems. E-mail me and I'll advise you of some good C4 info.

 

Use the C4. It is more than enough tranny for that 300 six cylinder. Sure the C6 is stronger, but it won't matter any, because the C-4 will take more than anything that 300 will every put out. The c6 would be like using a sledge hammer to pound in a nail. You don't need the overkill for your usage. Also, like it has already been said, grab the driveline while you are there. But, make sure the yokes are the same. If you have my luck, they won't be and you'll have to get your old driveline modified.