I have a 75 f100 4x4 390, np435, I found a 77 f250 4x4 400m, C6, for $500 bucks. I have not purchased it YET. The body is just a rust bucket. Was told it has a 400m in it. I really want the truck to swap out my 3.50 9in and dana 44, for the 4.10s in the rear and front from the 77. Is this a difficult swap? Will it work? Did the f250 come with limited slip because my 75 has a limited slip in the rear? Should I just keep what I got an save up to regear to 4.10s.

 

first off, there is no 400m, its just a 400. IMO i would take the f250 and remove the whole body if it is that bad. Clean, scape,paint,sand blast or what ever you can just to make it look nice,then change your body over and sell your running gear. Jack the F250 rear end of the ground, spin 1 tire, if the other spins the same way its a posi, if it spins the opposite its and open carrier. Good luck with it,and post pic's.

 

My 75 has a brand new built 390, and I want my np435 so I would have to swap that over to. Would it be easier to just swap the rear and front ends? And is it worth it?

 

IMO NO! All your gaining is 3 studs per wheel and more weight, i think its a waste of time and money.

 

Thanks bud

 

anythings possible to do...but ,its not even close to a direct bolt in swap. the f100 frame is set up for front coil springs. the f250 will have front leaf springs. it also makes a difference if the f250 is an early 77 model ( high boy) frame, or late 77 model (not a high boy) because the high boy has a narrower rear frame section , and a divorced transfer case.

 

X2 on NO its not worth it. Save the $500 for beer and gears for the F100.

 

Are you just using it as a play toy? The lighter the better off-road. Are you using it for towing? The heavier the better. Just depends on your use of the truck.

 

You could just swap in the Dana 60. Both trucks should have a Dana 44 front axle so you could just swap spindles, rotors, calipers etc on the front. Shouldn't be too bad. But unless you need a full floating rear axle I probably would not mess with it either.

 

The situations ya might think of going D60 is 37+ inch tires or terrain where the tires and steering can bind up like on boulder strewn trails. However, a good spotter and driving skill can make up for a lack of a D60.

Otherwise it's "Snap your fingers, snap an axle"... and have a winch.