Knocking during acceleration

I have a 1994 Cherokee, 6-cyliner w/180k miles. It just started making a knocking noise (sounds like you are riding on a flat) towards the front of the vehicle during acceleration. As soon as you let off the gas and the RPM's decrease the noise goes away. At first I thought I had a flat tire but it obviously was not the tires.

I had it in to a 4X4 shop after my local tire center said they couldn't fix it. The 4X4 shop is trying to get me to rebuild my transfer case which I think is a bit excessive. Plus, they said they could not guarantee that would be the problem.

Am hoping somebody out there has fixed a similar problem and can lend some advice.

Probably the same thing I'm facing. Keep an eye on my post and I'll watch yours. I feel your pain