First post so please bear with me if this question is out of line or misplaced.

I bought a used 1991 Ford F150 4X4, 5-speed 5.0L with no user manual for the specifications. I was hoping someone could tell me the rearend oil capacity of it. I need to change the gasket and wondered how much 90 weight I needed to buy. Thanks in advance.

 

Best I remember it was about 2.5 quarts, so buy 3. Check the sticker on the driver side door jamb to see if you have a limited slip axle or not. If you have one, you need to add 4 oz. of friction modifyer with the oil. You won't use exactly 2.5 quarts, just fill the rear until the oil level reaches the bottom of the fill hole. (if you have to add the modifyer, put that in, then fill with oil). A friend of mine owns the local NAPA store, and he recommended a GL4 or GL5 classification on the oil when I changed the gear oil in my truck.