I have a 91 ranger 4.0 4x4 with a 5 speed in it. I think the rearend is going out in it. I have the same truck but only it has an auto, for a parts truck. Are the rearends the same. I'm sure it would bolt up but is the gearing going to be the same? How do I check?

 

Yeah...it outta be the same, just check the ratios. There is SUPPOSED to be a tag in the far right side lower bolt with the ratio on it. It may be gone by now though lol.

If you look on the sticker on the inside of your door, it'll say something like rear or something to that effect. It'll be like 308 for 3.08 or like 3L55 for limited slip 3.55. You get the idea. Make sure yours matches the donor. If you switch sizes you'll need the little speed sensor on the rear diff as well I believe.

What makes you think your rear end is going out? It's a pretty bulletproof rear end for most anything it could be put through.

 

u should have an 8.8 if u have a 7.5, rounder bottom, then u could be looking at some damage, http://i2.photobucket.com/albums/y46...plorer%20Diff%, that is a 7.5 in a 3.0 1998, swaps are pretty straight forward and i know fullsizes have the vss in the axle but rangers do not, pull the cover and take a look, 10 minutes, report visual image, work from there, could just be your tranny bud

 

We have a VSS in the rear end as well. It's not just the fullsizes. Crawl under there and look.

 

You can also check the ratio by jacking up the rear and rotating the driveshaft. If the driveshaft rotates a little over four times for every complete wheel revolution, you have 4.10's. You get the idea. You do not want to put different ratios in the front and back!
I believe 4X4 and 4X2 are the same rear differentials.
There may be a difference in ABS and non-ABS rear axles.

 

Yeah if ABS was an option...Though I'd assume it wouldn't matter, unless you had RABS in which case you would have to get a RABS rear axle. If you didn't have it to begin with, you could get either since it's not going to work either way without you installing the whole system yourself.