How do I replace rear differential fluid after replacing gasket in 96 explorer

Look for plug on rearend housing. Should be able to put ratchet in the square hole and unscrew.

You will also need a hand pump (easiest) with a tube to insert into the hold. I believe you fill it until the gear oil begins running out of the fill hole. Once it stops dripping, insert the plug. Just make sure the vehicle is level when refilling.

There is no plug anywhere on the housing How much oil and what type

My 96 uses 75-90 gear oil. Best to check with a service dept at ford because they may have updated the requirement. Not for the filler hole. Lay on your back at the rear of the vehicle and slide yourself under until your under the differential looking up. You will see where the drive shaft connects with the differential. Use your right hand and slide it up along the differential until you get just above the driveshaft. The differential will have a lip or ledge prodruding. Feel around with your fingertips and you will feel the fill hole. If memory serves mine was a square hole plug and I used a socket extension rod to take it out.