8 3/4 gear set up help

Since you didn't mention it, how are you measuring pinion depth?

Sounds like you are using the measurement on the gears, putting it together and then using the pattern to check where you are.

IMO, the only real way to take the guess work out of it is to measure pinion depth off of the carrier bearing races. That way you will get the exact relationship of the gearset to the case which is what pinion depth is. You need to verify that before you start adding or removing shims.

Also, there is a specific baby-**** yellow marking compound used for checking gears. Prussian Blue is more of a machining/valve seat reference, might be the wrong consistency to get an accurate pattern. I could be wrong on this but I've never seen blue used for this purpose. Every gear set I've dealt with comes with a package of that yellow crap.