I suspect your pinion is too far out and the shims on your carrier bearings are incorrect.
I get the feeling you are adjusting backlash by just changing pinion shims, and that's not going to fix your problem. Follow the dana procedure, but I suspect you need to move the ring gear closer to the pinion using carrier bearing shims and reduce your pinion shims to pull the backlash.
You hear it all over the place that coast is the most important. I suspect that is just from a mechanics perspective, because a noisy R&P is going to bring that rig back into the shop. I get my drive where I want it (centered face to flank and about 1/3 up from toe) and make sure the coast is reasonable. If the coast is unacceptable I might change my drive a bit or backlash to get it were it will be acceptable.
Follow the dana procedure for setting up your carrier bearing shim pack, I bet you will get the pattern you are looking for.