rearend interchange

[michael69]

I was wanting to know if the rearends in 73-79 f-100s are a direct bolt in or is there fab work involved. I know they are wider thats why I want to use newer rearend.

[FORDification]

No, the spring perches are 4" farther apart on the rearend housing. You'll have to weld new spring perches on to use them on a bumpside truck.

[michael69]

I guess I will just have to use offset wheels on back. Any suggestions on wheel width and offset to make rear look even with front.Whats needed on back if I have 8in. on front?

[sideoilerfe]

I guess I will just have to use offset wheels on back. Any suggestions on wheel width and offset to make rear look even with front.Whats needed on back if I have 8in. on front?

That's not what he was talking about. He was referring to the space in between the spring perches. The diffs should be the same.

[michael69]

I was talking about putting wider wheels on my 69 rear to make it look wider.

[FORDification]

I guess I will just have to use offset wheels on back. Any suggestions on wheel width and offset to make rear look even with front.Whats needed on back if I have 8in. on front?

That's not what he was talking about. He was referring to the space in between the spring perches. The diffs should be the same.

The F100 differential got 4" wider overall in '73, which brought the rear wheels out far enough to line up behind the fronts.

These are from a '73 factory brochure:





I can't speak specifically on the proper offset to use, but generally speaking you'd just need to add about a 2" additional offset on each side to get the rears to track behind the fronts.

[1971ford]

cool so i could have my dad search bumps AND dents for rearend for my truck (because i want 3.73's). ill just have to take it down to the welding shop i work at and have the mounts moved. or do i need new leaf spring mounts? are the leaves wider or the same?

[FORDification]

It would be easy enough to cut the existing spring pads off the rearend housing and just move them out the proper distance. However, make sure you get them in the correct spot, as their location will affect the pinion angle.

The dentside leaves are wider as well. You could use them but you'd also have to salvage the frame brackets from the donor truck.

[mrtleavitt]

Would the wider stance reduce wheel hop in any way? I'm thinking not but there might be something I'm not getting.