I'd like to improve highway speed. Read through some threads discussing rear end swaps and have a couple questions. My 56 has a 272 with stock 4 speed and drive train. If I understand right, a 57-60 F100 rear end will bolt in fairly easily. Will that give me slower rpm at highway speeds? Another option I've seen is an aftermarket overdrive kit. Any thoughts on doing this vice the rear end change? Thanks for the help.

 

The 57-72 F-100 9" is as close to a direct bolt in as you'll find. Depending on your application and what parts you get with the housing, you may need to make some shock mount and driveshaft mods. But the rear itself is the same width and bolt right up to the existing springs.

Whether or not it will change your highway engine speed will depend totally on the differences in the gear ratios in both rears.

 

Like 52merc said, the pre 73 9" will basically bolt right in and, if you look around, they can usually be had for under $200. Much cheaper than an overdrive unit, and almost a direct bolt-in.

 

Thanks for the responses. If I understand some of the threads correctly the ford 9" gearing is easier to modify than mine or if I get lucky I can find one with better ratio for highway use. Guess I'll begin checking out the local wrecking yards.

 

I recently bought a 9 inch for my 56. What is the story regarding the shock mount plate that goes under the axle housing on the original axle? Can I use that to just bolt the new reared on?

 

Hi,


I'm swapping a 1972 9" into my 56 F100 and it is pretty straight forward... the question I have is what did everyone use for a U-Bolt? I'm keeping the stock suspension 1 3/4 leaf springs and the 9" has 3" tubing so I have a set of lower mounting plates for a 57-62 F100, which used the 9", but they used 2 1/4 leaf springs. If I use U-bolts from the 57-62 era then I have 1/2 of play around the leaf springs and that seems like the springs might 'walk around' after awhile. I'm considering welding some 1/4 steel to the U-Bolts... is there a better solution??


Thanks!