My bother-in-law has a 1976 F150 4X4 with a four speed and 300 cu. in engine. The 6 cyl engine needs a complete overhaul. He also has a 1970 F250 two wheel drive with a good 390 and four speed. The body on the 1970 is shot. He wants to put the 390 in the 1976 in place of the 300. He is on a tight budget and merely wants a cheap 4X4. What changes are required to do this swap? It appears that I'll need to get a rear sump pan for a 390 4X4 and use the 390 bell housing and clutch assembly. Am I correct? Will the 6 cyl transmission bolt to the V8 bell housing? What about clutch linkage? Both have manual linkage and look similar. Any recommendations will be appreciated.

 

Widall, I want to be first on your list. I need those 300 engine perch's.

I'm slowly working toward a 300 to replace my 460.

On which bell housings fit, do a few searches through these kind of threads.
Which ones fit has been repeated many times.
As I remember though, the 300 and 390 blocks are different.
If you are a contortionist you can measure across the top two bolts at the bell housing. That will tell the tale for you.
Personally, I think rebuilding the 300 would be a better deal.

 

NOt sure about manuals, but the 300, 302, and 351w use the same bell. 351m, 400, 460 use big block bell, and 390 uses fe bell. However I think you can reuse the 300 perches, you just have to move it back one set of holes. JMO Someone correct me if I'm wrong, Good Luck,
Dave

 

Thanks for the information. I'm having a bit of trouble finding a rear sump pan for the 390. If I have measured correctly the 6 cyl transmission has the same bolt pattern as the V8. The bell housings are different.