Frame ?

[sparkisimo]

Does anybody happen to know what the difference between a 2wd frame and a 4wd frame might be?
I bought a 77 F-150, 2wd with a blown engine for the body and after a closer look the frame is also in much better shape than mine.
At first glance they seem to be identical, the 4wd is a 78 F-150.

 

[lsr490]

I'm not sure about 70s and 80s frames, but on 90s and later the thickness of the metal was seveal thousands of an inch thicker on Lightning and 4x frames. If you could measure the frame rails of both frames with a dail caliper you could answer this for both of us.
Thanks,
Bill

 

[off-road mudrunner]

you will need to measure frame at sezeral points. most 4x frames where wider at front end