Driver's side of differntial, mid-way up case. You'll see a pipe threaded plug.
front or rear? the front is slightly higher and rear of the drain... the back has a cover you remove to drain the fluid and a fill on the front of the diff..
It is in the center of the differential cover.
It is a rubber plug in the front cover.
The fill plug is on the drivers side, front of the differential. It faces toward the drivers side wheel. Check your owners manual for proper fill level, I believe it is 9/16" below the plug.
On the front, about 3" up. On mine it was a 24mm nut.
You unscrew the plug on the front cover, and ad 75w90 to the bottom of the hole.
there is a drain (on the bottom) and fill plug (toward the top) for the front differential. 1.6 quarts of 75W90 GL-4 or GL5 gear oil.
Remove the fill plug from the 2001 Explorer differential. Remove the cover from the head to allow the fluid to drain. put the cover back on with a new gasket, then fill the unit up through the fill hole.
3 1/4 qts. or fill until the oil starts to come out the bottom of the fill hole.
The 2002 Ford F2 50 rear differential has and oil capacity of 5.5 quarts. You can check the oil level through the oil fill hole.
Just fill it until the lube runs out the fill hole. It is now full.
The only place you would use gear oil is in the rear differential and or front differential if it is a 4+4. The differentials have a fill plug.