Same place you check it.
Just fill it until the lube runs out the fill hole. It is now full.
It is in behind the oil fill cap in the fill housing.
The fill plug is on the rear cover of the differential. Remove the rear cover to drain the fluid.
The 2002 Dodge Ram 1500 PU came equipped with the 6F55 6-speed automatic transmission. The total service fill for this transmission is 11.6 quarts.
The rear axle fill plug is the rubber plug in the rear differential cover. Fill the fluid to the bottom of the hole. 75w90 or 80w90, if posi it requires a limited slip additive.
18.7 liters in a radiator flush and fill in a 2004 Dodge Ram 1500.
Through the check plug hole in the rear of the cover.
You will see 2 plugs on transfer case, the lower is to drain, upper is to fill or check level
You unscrew the plug on the front cover, and ad 75w90 to the bottom of the hole.
Remove rear axle cover, oil will drain out, reseal and install cover, fill fluid.Remove rear axle cover, oil will drain out, reseal and install cover, fill fluid.
You add fluid at the same place you check the level.