Great info, thank you Workingonit...I think I used that same gear mesh pattern picture when checking mine. the front is quite good, I think, but the rear is shifted to the heel a bit.

Two notes: no whine at all today when I drove the X5 to the store here at home. Its 65 degrees though so I wonder if the gears in the diff don't like 25 degree oil? Also, I've been running Amsoil Severe Gear and went to order two new bags of it (much easier to squeeze into the diffs from underneath), but I noticed that it has friction modifiers in it. Not sure how I missed this.
The quaife isn't an LSD so friction modifiers are not called for. I'll grab some red line from my local AutoZone tomorrow when I change the fluid.

Also, that gear driven top end must have been a monster! I watched something where Gorden Murray was talking about the Cosworth V12 in his T50 car. The Cosworth guy being interviewed said that for RPM above 10k (I think) you need a gear driven valve train. That motor spins to over 12k. crazy.

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Current
Original owner 2002 E53 X5 4.4i to 4.6i swap
2026 G80 M3 6 spd
2025 G06 X5 50e
Former
1972 Audi Fox
1986 Saab 900S
1996 BMW Z3
1998 BMW E36 M3 Sedan
2004 BMW E46 M3
2006 Audi A3 Quatro
1993 Mopar 318 Jeep Grand Cherokee
2015 V6 Jeep Grand Cherokee