going to look at a rear end later this week and the only info that I can get from the guy is that it's a 3.73 8.8" Ford HD 31 spline posi. 4.5" bolt circle, 59" wide.

He doesn't know what it came off of. Anyone know if this would bolt-up to my 1996 f150 with 2wd and a E4OD? Would appreciate any help.
Thanks

 

4.5" bolt circle and 31 splines would suggest to me this is a Mustang or Mark VII rear axle. Trucks use 5.5" bolt circle, not sure on the splines, but I think they are 31 too. If splines match, you can always pull the differential and gears from the new ale you're buying, and drop them in your truck's factory axle.

 

Would I be able to drop the new ones in fairly easily, or would it be the same as installing new gears where I have to really get into to some work. I was hoping that I could find a rear end like the one I mentioned and do exactly what you suggested.

If I keep everything intact and the splines match would that make the swap alot easier, because I helped a friend swap to 4.10's years ago and that was a pain and I didn't pay attention much either so if I can drop in the parts from this rear I'm looking to buy that would be great.

 

It could have also come from an explorer or ranger, but I think it will be too narrow regardless. If it's the gears and differential you're interested in, swapping them into your factory axle as M.L.S.C. suggested is probably the best bet. I would think that they need to be setup like a new set of gears, but I don't know that for sure. The 8.8 used in F150s should have 31 spline axles too.

 

If you are planning on swapping in the gears and carrier it will be just like installing a new set. You stand a pretty good chance not having to change the pinion shim depth. Ford is pretty good at keeping the axle housing tolerances consistent. Same thing for the carrier shims, it may take some moving a shim or two from one side to the other to get the correct backlash.

 

For someone like myself that has a Haynes manual, good mechanical inclination, fair amount of tools how hard is swapping the rear to do and what type of time would you allow for a first time swap.
I've rebuilt a good number of pumps and stuff, but really haven't messed to much with my trucks past the bolt-ons.

Swapping the rear-end and the cam are the two things that kinds of intimidate me because I really haven't watched either be done. When my buddy did his rear-end swap I was just giving him a hand when he needed it, and welding some stuff for my Bronco while he was doing most of the figuring.

I really want to swap the cam and the gears, but keep avoiding both. Paying someone else is out of the question. Not because I don't have the money, but I want to see how it all goes together.

What do you guys think, are these installs over my head?

 

It is not that difficult to install new gears as long as you understand the concepts and have patience. The last gear swap I did in my home garage with no air tools. I rebuilt the Trac-Loc clutches and installed 3.73 gears into the wife's '97 Mustang GT.

I already had a dial indicator and stand, inch and foot/lb. torque wrenches, long breaker bars and big sockets. I used a 3 foot long piece of angle iron to hold the pinion yoke when removing and installing the pinion nut and setting the pinion preload. It took two trips to the local machine shop to install new bearings and get the pinion depth correct. Your results may vary. It does take time, it is messy and without air tools it can be a muscle strain. Hint: it is much easier to do this with the rearend on a workbench.

I am also not one to farm car repairs out to someone else. I also had the luxury of more than 3 cars for two drivers available. Only you (or the significant other) can be the judge if you want to tackle this or not.

 

How often do those clutches go out. I've heard 30k-50k from some, but they don't drive like most folks do.

What about installing a cam, anyone have advice or insight on that endeavor?

 

50K sounds about right for the clutches. That reminds me...I have +70k on the rebuilt rear in the Mustang now. Cam swap is another do-able home garage swap. Get some manuals, read some threads. Arm yourself with as much info as possible. Always plan to change as many gaskets as possible while you have the top end apart. Same for the water pump. If it has some age and miles on it, swap in a new one

 

Sounds like I am waaay over due at 190,000