I have an 10 bolt, 8,2 "B" with a heavy duty posi (4 spider gears), I know it will need a posi addative, but is it the basic 80-90 gear lube thats used too?

Thanks

 

With any friction type posi unit, be it cones (auburn) or clutches (eaton) you would be wise to use the mineral based (standard gear fluid used for years and years) with at the very least 4oz of additive. You will probably need 6-8 with the HD unit.

Yours is a cone type unit if it the 4 spider gear type and looks like the picture below. Jim

The weight is not really a big deal usually a preference of climate your in. hot all th etime 85-140w cold and hot climate 80-90w

Good luck and this info maybe too late for you but still may help someone else out in the future.