original gearing ??
whats in your car now ??
pop the cover off
and look on the ring gear on the originals ... tooth count is stamped in the ring gear edge
if you dont know anything about it
drain it .....
buy a gasket and 2 quarts of 80 90 valvoline and fill till it runs out the fill hole...
wire brush or power wash the seal area BEFORE taking the cover off
and around the filler hole plug so no debris gets in
yah theres stamps on the tube and casting numbers ... and yopu can spin the tire and count and divide ..............
just pull the cover... change the lube make sure to clean the oil out of the bottom of the carrier
and wipe the bottom floor of the housing clean with brake clean on a rag ....and a screw driver
all the heavys with fall and be there layin on the bottom