Knocking sound at the back end every time I try to Move forward

Does your driveshaft climb at a steep angle from the rear differential to the transfer case?

What kind of condition are your shackle and spring bushings in?

You might have a pal watch one side or the other (or you) while the other shifts from reverse to forward looking for any movements that should be holding steadfast.

I had a clunk in my Jeep when I would start forward from a stop. My driveshaft was pretty steep on my CJ-5 with a 2" spring lift (A CJ-7 is longer it would not have been as steep- but I have a "5"!). The front of my differential was torquing downward as the driveshaft/ universal joints were almost in a bind as it turned.

The fix was to attempt to aim the rear pinion upward pointing more at a straight shot towards the yoke of the transfer case. 4 degree axle shims got it closer (even though it was not perfect, the binding was eliminated.

I took some pictures. I failed to take them of the shims before I put them in.

My axles are factory on top/ inside my leaf springs (some people do a "spring over" whereas the put the axle under the spring to gain lift)

My shims are place on top of the spring the perch on the bottom side of my axle indexes into center. The wide/ or fat part of the shim is closest to the front end of the Jeep. This rolls the axle 4 degrees so that the pinon rises further from the ground.

I also failed to use a tape measure to show the progress in my pictures that I did take.

So,

Check this out! I sat my camera on the spring in the same spot.

Picture 1) is before the shims.

Picture 2) is after the shims.

The tire flat on the concrete in the background never moved, eyeball the front bottom of my differential to the treads on that tire, same goes for the jack stand. It doesn't look like much looking at the pics, but it made a world of difference.

Let us know what you come across.

The Medic