Not sure of the bolt patterns or sizing for the fill and drain plugs on the GTO for the diff and tranny. On my Corvette, they are some weird sizes. For example, the diff fill plug is a 10 mm hex allen bolt head. Not something I had in my tool box first time around. I suggest that if you do this yourself, you ensure you can get off the fill plug before you open the drain plug. You don't want to find yourself in your driveway with no fluid in the tranny and no tool in the toolbox to open the fill plug...
You'll also need something like this to pump the fluid up into the diff and tranny:
AMSOIL Hand Pump
