I have slop in my drive train somewhere. at any speed i get a pretty good klunk if I apply and release the accelerator. Is this coming from the chain in my Transfer case? I couldn't seem to find any play in the rear diff or U-joints.

 

I don't know why my sig isn't coming up but its an 87 S-10, 2.8 EFI

 

I just changed the oil.. replaced it with 10w-30 quakerstate synthetic blend, 4X4 - SUV. it has 200k miles, Is that a good oil?...

Back to the diff. I filled the rear diff with 80W 90 it was a quart low. Does the front diff take the same weight?

 

Check for a loose u-joint.

That is expensive oil. I still run regular old 5w-30 Valvoline or Castrol GTX.

Yes, the front dif is the same. Gear oil.