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I am swapping my 81 F-150 frame for a 90 F-350 frame I am also shortening the frame to 6 foot bed. I was wondering if there were any differences in these to frames other then the thickness of the frame or the length.
The F350 rails will be a bit taller, and wider, but, all the mounting dimensions are the same. However, depending on what engine the F350 had, the engine crossmember may be different. 460/diesel trucks have a specific crossmember. All V8 engine mounts will bolt to it however. 300 ones however, the pass. side should bolt on, but, at least one bolthole on the drivers side the bracket won't even be touching the crossmember.
The F350 rails will be a bit taller, and wider, but, all the mounting dimensions are the same. However, depending on what engine the F350 had, the engine crossmember may be different. 460/diesel trucks have a specific crossmember. All V8 engine mounts will bolt to it however. 300 ones however, the pass. side should bolt on, but, at least one bolthole on the drivers side the bracket won't even be touching the crossmember.
I bought a pair of F250 300 frame mounts and the diesel/460 crossmember is different.
the top 2 holes on the passenger side line right up. the bottom two holes need to be drilled.
The drivers side tower it a huge pain in the butt. no holes line up. it sits perfect on the crossmember but the top 2 holes and the rear lower hole need to be drilled. the front lower bolt hole sits right over a gap in the crossmember, so you will need to weld in a piece to bolt it too.