Really dumb axle question...

I'm sure this has already been done, but I'm not sure how to phrase the search, and I needed to use up my "dumb question quota" anyhow (how many are we allowed per year? I've got four or five years' worth stored up...)

Anyhow, I just had my 88 up on a lift last week (1988 2dr Laredo/4.0/BA10/NP231/D30/D35) at school, and I've been beating my brains out on this...

The front tyres, spun by hand - spin one forward, they both go forward. Spin one backward, both go backward. Didn't hold one and spin the other - forgot to and class ran out.

The rear tyres - spin one forward, other goes backward. Hold one, other doesn't spin.

I haven't added anything to either axle but oil, and I don't remember seeing anything unusual at prior services. I'd have to crawl under to read the tag (I know the rear one's still there,) and according to the previous owner, nothing had been changed.

What are the odds I've got some sort of LSD in the rear, or do I need to post more information? I've been thinking on and off for the best part of a week, but I've had my head wrapped around engines long enough that I've forgotten basic axle tech, and I'm not sure where to look...

I can post Dana BoM numbers (as available) in the next couple days, if requested. I'd have to find the list I did in Excel before I could use it - unless the Dana Expert site is still public... Just thought I'd try here first.

5-90

Driveshaft is spinning on front one, allowing both tires to move together. Driveshaft in rear is held by the trans, forcing the diff to spin the tires in opposite directions.

Normal open diff operation on both ends.

Rev

Thanks - I knew it was something simple and stupid, and I didn't figure on being that lucky. I just don't "think axle" enough to pull this one right off the top of my head!

5-90

So, if driving and one wheel is locked up in the rear, the other will spin just fine? You could drive with 1 wheel power only? Won't damage anything?

pancake said:

So, if driving and one wheel is locked up in the rear, the other will spin just fine? You could drive with 1 wheel power only? Won't damage anything?

Click to expand...

It won't do the diff any good, and it will chew the tire off, but yes, it would run with one wheel locked. In theory, I suppose, if you developed a terrible problem with one wheel or tire, you could lock it on to one of those dollies tow trucks use for severely damaged tows, and drive it home on the other wheel.

pancake said:

So, if driving and one wheel is locked up in the rear, the other will spin just fine? You could drive with 1 wheel power only? Won't damage anything?

Click to expand...

Exactlly why you will go nowhere with one wheel in the air.

Rev

pancake said:

So, if driving and one wheel is locked up in the rear, the other will spin just fine? You could drive with 1 wheel power only? Won't damage anything?

Click to expand...

Unless your diffs are locked.