closed knuckle to open knuckle swap question

[71highboy]

hi.i have a 1971 3/4 ton 4x4 and i want to change my front closed knuckle differential and put in a open knuckle unit.any suggestions on what years will bolt up without a lot of modifi cations.thank you

[averagef250]

1976 to 1977.5 F-250 4x4 is a close swap. You will need to update brake hoses, proportioning valve and master cylinder for discs. 1977.5-1979 will work with the addition of shortening the front driveshaft.

[71highboy]

great thank you very much

[BRUTUS_T_HOG]

1976 to 1977.5 F-250 4x4 is a close swap. You will need to update brake hoses, proportioning valve and master cylinder for discs. 1977.5-1979 will work with the addition of shortening the front driveshaft.

i believe you also have to either modify the steering knuckles to accept your tie rod ends or you have to use the 76-77 pitman arm and steering linkages. at least thats what i got out of my research, im doing the same swap when i find an axle

[71highboy]

ok thanks brutus

[averagef250]

1976 to 1977.5 F-250 4x4 is a close swap. You will need to update brake hoses, proportioning valve and master cylinder for discs. 1977.5-1979 will work with the addition of shortening the front driveshaft.

i believe you also have to either modify the steering knuckles to accept your tie rod ends or you have to use the 76-77 pitman arm and steering linkages. at least thats what i got out of my research, im doing the same swap when i find an axle

There are several sizes of american pickup (non metric 1.5 inch per foot) tie rod tapers. The 76-77.5 stuff should be the same as the all the older closed knuckle stuff. The 78-79 stuff may use theslightly larger tie rod ends.

Both of those sizes are on the weeny side, they aren't very far apart and easy to ream larger or slip a washer under the stud to take up some slack so the nut will tighten.

The reason why a guy might want to add the 76-77 F-250 4x4 pitman arm to his older highboy when swapping in any open knuckle front end is because the open knuckle axles use a longer steering arm, the 76-77 pitman is a tad longer to maintain full lock-lock steering.

[71highboy]

ok thanks everyone. very helpful