Front driveshaft turns when I spin driver's wheel in 2wd?

Recently an issue cropped up with my truck where it pulled to the left when braking. I also noticed that sometimes the steering feels like it's binding a bit at low speeds.

While I had the front wheels up in the air (and was in 2wd), I noticed something (probably has nothing to do with the braking issue, but still).

When I spin the driver's side wheel, it mostly spins freely, but at a couple points, maybe twice per revolution, it seems to hit a friction point where it causes the front drive shaft to spin a little bit, too.

If I hold the driveshaft tight in my hand and spin the driver's side wheel, I can still spin the wheel freely, pushing past that friction point.

This happens with both the passenger's side on the ground and in the air.

I can spin the passenger's side wheel and it does nothing to the front driveshaft.

Also, if I spin the front driveshaft with my hand, it spins pretty freely and the wheels don't move.

I recently noticed that there's a bit of oil around the where the passenger CV connects to the diff (leaking seal), so it's possible that low diff oil is causing this.

Or it's possible I'm worried about nothing. Has anyone else noticed this behavior in their front driveshaft?

 

So uh, a few years later I have the same question.

 

If anyone stumbles on this thread, a little searching and I found the answer: "to elaborate, the ADD decouples the passenger side front driveline between the diff and inner CV"

 

Locking hubs or add hubs?

 

ADD, so makes sense, right?!

 

I think so, but I'm not an add expert. Mine has manual hubs.

 

Yup

 

Manual ADD in 2WD in cold temps in neutral the truck moves with out the parking brake applied .

Enough surface tension in the gear oil to hold things enough.

 

Normal