I upgraded my fuel pump yesterday and the tank had a little less than 1/2 (very heavy). Luckily my brother helped me out. It's pretty easy and can be done in less than and hour with two capable people. Syphon as much gas as you can. Relieve fuel pressure and disconnect negative cable. Take off the bolts holding the filler neck from the top and from the bottom (inner fender). Jack up the car on stands, put a jack with a piece of wood under the tank, lift and support it, remove two bracket bolts (13mm), move brackets aside and carefully lower the tank. Sender unit is the piece in the middle of the tank the one on the right is the fuel pump. Sending unit has a locking crown looking thing holding the unit down, hit it with a punch or a flat head screwdriver and a hammer so it turns counter clockwise. Disconnect, remove, and replace unit as well as the o-ring, it really helps to put it back together if you can get most of the gas out with a hand pump or something similar. Installation is the reverse of removal.
