There were a few 1973 early 1974's because I noticed a few with four screws on the tailamps. I also noticed a few without Custom Badges or holes on the back, (That I could see). This suggests 1976 truck with the 73-75 grille inserts. Very easy to swap the grille inserts out. They also removed the ford lettering from the grille too.
So anywhere between 1973-1976 would be plausable. []

Cooters tow truck...

Early episodes he drives a 1967-1972 Chevy. Either blue on white, or Brown.

Later on he used a 1978 and/or 1979 F-350.

He's also seen using a 1967 F-350, blue on white, tow truck, painted simular to the chevy.

Lot's of 1973-1979 Ford Trucks in this show. []