[Ray Menard]

I run a 9" Ford with 6:20 Gears @ 9800 RPM (1/4 mile). I use Lubrication Engineers Gear Lube 607 ALMASOL (ISO VG 220/SAE 90/AGMA 5EP). Roger Lamb carries it. Any lube will do a reasonable job, however, I settled on the ALMOSOL by using this simple test:

On a Test N' Tune day, with your current lube in the case, make a pass
After your 2nd pass of the day (to account for heat-sink), safely pull off to the side of the "return" road
Using your Infra-Red Temp Gun, get a reading from the case

On the same day, change to your chosen replacement lube
Make your 3rd pass, pull off etc., etc.

The lowest temp reading indicates the best friction control.

Hope this helps.