I have a 98 1500 2wd Ram with 198k.
Rear end started whinning so I was looking at just replacing it with a good lower mileage used rear end assembly. I went to go checkout out one I found on craigslist. The previous owner had the assembly from a 99 1500 2wd on a bench and didn't know for sure the ratio. So I was trying to calculate the ratio by turning the axle shaft 1 revolution and count the pinion revolutions. But the pinion shaft doesn't turn when I do this just the axles. When I turn the pinion yoke both axles turn and I get 4 and 1/8 turns of the pinion yoke turn to one revolution of the wheel. I found a factory sticker on the axle tube with p/n's and 3.55 on the sticker but turning the pinion didn't match up with what the sticker was saying. I removed the cover and counted the ring and pinion teeth and found out this is a 3.55 axle ratio (11 pinion teeth to 39 ring gear teeth) Looking at the carrier I didn't see anything out of the ordinary, nothing broken or metal in the bottom of the differential, the oil did look suspiciously clean though.

Questions: How come the pinion shaft doesn't turn when turning either axle? How come turning pinion shaft approx. 3 1/2 turns is only 3/4 revolution of the wheel? I believe this is a limited slip differential it has side gears and spider gears in the carrier, Is this how you can tell visually?

 

The LSD has a clutch pack right behind each side gear, no clutch packs is an open diff. Both diff.s have the gears.

 

So you can visibly see the clutch pack under the side gear without having to take out the carrier to verify.
How thick is one side of the clutch pack? 1/8", 3/16", 1/4" etc.

 

You can see it without taking out the carrier, between 1/2" and 5/8ths thick for the pack.

 

Nice pic!
So do you think something is wrong with diff. I went to look at because the pinion shaft yoke doesn't turn with wheel rotation either direction.

 

It shouldn't. It'll turn the opposite wheel the other way. Have a buddy hold the passenger side axle.