If you have a posi for the street I would use 75W90WT HD gear oil with a posi additive, with a spool straight HD gear oil . Fill it up to the filler hole for your own peace of mind Mopar use to recommend for a drag race only Dana 60 and in the 8 3/4 to use one quart only They, the Hi Po Drag race team, said the rest of the lube in the rear end housing was to elementate noise, to keep the average car owner happy I use to fill my strret and strip Dana 60 up all the way to the fill hole cold with Scheiffers(SP?) GL5, I ended up draining it out the drain hole several times to inspect the fluid and ended up trying 1.5 Quarts only, no noticeable differences in performance or noise That was with a Strange Engr. 35 spline spool and axles, not a posi., with stock OEM Dana Corp. 4.10 gears