in the past I have used the ratech pinion depth tool,however I seem to remember loaning it out and now I dont have it.anyway I decided to use the MHD method which is basically measuring the old pinion head and shim,and then measuring the new frpp pinion head,and coming up with the appropriate shim to get to the same depth.well I did that and the math was telling me to decrease the shim from .036 which was the old shim to .015 on the new pinion,but after doing that and trying a mock up the pattern is kinda high and out towards the heel,so I decided to try a mock up with the old shim,and the pattern looks much better.I dont get it. the thickness of the new head is 2.895 and the thickness of the old head was 2.874 without the shim,so how is it that the old shim is showing an acceptable pattern? could it be because the new 410 pinion head is much smaller in circumference ? I would think that wouldnt matter because the new ring is thicker.