You are a lot closer than you think. Don't change anything yet. I cant see the pattern on the drive side very well, you don't have enough load on the ring gear. The shadow I do see looks like it is wide in all directions and positioned to the toe. If that is it you are there. I cant see it however so it is very possible "wishful thinking"! The coast side is too deep. That will howl when you back off the gas. Get the drive side first. Make sure the backlash is correct. On a used gear set use the larger specification for backlash (.010"). We might tweak the coast side with the backlash. More on that later if needed.

You are on track. The number was twenty thousands on the shim. Lets see what a good clear mark looks like. More drag on the ring gear. You should not be able to turn the pinion easily by hand. If you are pushing something against the ring gear, be careful you don't want to crack the axle housing. Use a wedge block of wood (like a doorstop) or nylon against the ring gear and the case. I did see a guy break the case using a crowbar against the ring gear. Roll the ring and pinion several revolutions with load. Look for the marks on the opposite side of the paint spot. See what the marks look like out of the paint. Your getting close. Shoot pics of the painted spot and the unpainted spots where the gear transfers the paint.

If you have the preload set on the carrier bearings (you should have .015" of preload), just move shims from one side to the other to change backlash. Keep the total shim pack the same. So take from one side and add them to the other.