I think my project just became my parts truck! My dad ordered a 77 F-150 4x4 new in 76. It was supposed to come with dual tanks but when it showed up at the dealership it only had the rear. They installed an aftermarket saddle tank that wrapped around the frame like a horseshoe, and, guess what, held dirt for 30 years. I finally acquired the truck from him and have slowly been working on it. Yesterday i pulled that tank out, and found exactly what i suspected. Frame Rot! The bottom couple inches of the frame is completely rotted out in one spot, about an inch and a half wide. Then above that the frame is cracked at least halfway to the top of the frame. I know i could cut that part out, patch it, and fish plate it, but there was also scaly rust on the frame for about 2 feet, the whole length of that tank, that im sure weakened that part of the frame also. That is a big area to splice in and would require fish plates in 2 different spots. I'm really thinking of just starting completely over. I wanted to fix this truck up nice for a driver, but need to at least replace engine, seat, and box anyway. I'm thinking i may just start over with a frame that i already have stripped, have it cleaned up and painted, and start going back together with new polyeurethane suspension bushings. I have new springs i was going to put in, and can swap the axles in when im ready. I have the new box and think i can find a cab and front clip in good shape pretty easy. That would make for a better job and not have this truck scattered out everywhere as i tear it completely apart.

 

Bummer! Especially since its been in the family since it was new! At least using it as a parts truck you would still have the original, at least partially! It sound like you have a lot of work ahead of you. Best of luck!
Dak