A few questions on setting up a 12 bolt.

Do you HAVE to measure the pinion depth or can you just use the gear pattern? It seems that the measuring just gets you close to the correct depth and then the gear wear pattern fine tunes the pinion depth. Is the accurate?

Is .009 too much backlash on a used set of gears?

Does pinion depth effect backlash? It seems that it would to a small amount being that the gear tooth on the pinion is thicker towards the rear of the gear.

I'm asking because I am having some odd noises after having my pinion seal replaced. The shop found some shims under the yoke that they thought were mistakenly put there instead of behind the pinion bearing to set the pinion depth. No other changes were made other than moving these shims. I saw the shop check the bearing preload so I thought everything was okay. A couple of days later the rear started making a lot of noise that is best described as "slop". Gear whine has not changed much, it just sounds like there is a lot of play in the rear. I took it back and the pinion nut had backed off about a 1/16th of a turn. This was tightened back up and lock-tite was used. Last weekend I checked it and it had not backed off again and I checked the backlash. It was .009. This weeked I am going to get a basic kit and replace the crush sleeve, pinion nut and check to gear pattern with compound (I could not get any last weekend). I'm really worried about tearing up the pinion bearing as I am driving aver a 1000 miles a week right now. I'm thinking that either the pinion depth is not right (should be close though) or the pinion bearing preload is too loose.

Any suggestions. I know the "right way" to fix this is new gears and bearing, but I can't afford that right now.