There is a drain plug at the very bottom of the tranny. Open it up and drain the fluid as per usual, then reinstall the plug. On the passenger side of the tranny is another plug half way up the side of the tranny that you remove for refilling the tranny. Pour the fluid in until it starts to run out the same fill plug hole, then reinstall the plug and you're done. The easy way to get the fluid in there is to go to a boat and motor retailer/supplier and buy a hand pump that is used for oil filling stern drives. It attaches to the top of a standard quart oil container and has a foot lenght of clear hose that you can place in the tranny filler opening. Then simply pump the plunger on the top of the oil container to fill the tranny to the level needed. You'll be able to use the pump and exactly the same method on your rear end diffy. Good Luck!
