I have a '56 F100 frame that is unuseable, I located a '59 F100 frame nearby and was wondering if they would interchange easily. And by easily I mean with minimal modification. Anybody on here with experiance in this swap?

 

i'd think 53 54 55 56 is the frames you need to target ...the 57 and later the brake and clutch pedels are hung under the dash ,, you'll need to move your brake/clutch pedel quadrent to the new frame master cylinder .. and i'd think the radiator mount U for openers ,

 

This subject came up not too long ago and there was a picture posted of a 57-60 vintage and there is a difference in the front cross members and definatly the cab mounts. You would be better off looking for a 53-56 frame as mentioned, where the only difference is the length of the rear leaf springs on the 55-56 model years which shouldn't creat any problems for you. With all the parts trucks out there you should be able to come up with the proper frame that would eliminate the headaches you'll run into with the later frames.