I have to replace the steering box on my 1977 F-150 and need to know what years will interchange. I appreciate the help.

 

Search this forum. I think there's already a lot of info on this. The best bet is to go with a later box. Can't remember for sure, but somewhere around 80 to 82 Ford went back to putting bearings on the sector shaft and they are a lot better box. Not sure when they started doing it, but my 79 F150 had no sector shaft bearings from the factory. It was machine fit to the housing and used the inside of the steering gear at two points for load bearing. It didn't take but a few years and the housing would wear egg-shaped and the leaking begins.

Texas Bird

 

Check the top of the steering forum. They have a link in the READ FIRST post about HD steering boxes with the bearings. That may give you the answer your looking for.