A 5mm Allen T-handle didn't fit my filler plug but a 3/16" did.. ?
Anyways, I used an AirBoy/JWL fluid suckereruperer which uses compressed air to create a vacuum, and that vacuumed out every drop from the gear case.
These vacuum suckers are fantastic at removing fluid like the time/s when you accidentally over-fill a power steering reservior.
I bought my AC-Delco/GM 12345982 fluid from an eBay seller in the USA. I bought 4 bottles, postage paid, for AU$60. So this oil change cost me $30, or through GMH, it would have cost me $72 at $36 a bottle!!
..and 2 bottles/8oz/238mls are required for 1 complete fill.
They came with these cool pouring nozzles which made the filling a cinch.
The fluid is almost completely clear and the 2 bottles get it right up to the threads..
~220mls of this brown looking crappola was sucked out. I'm guessing it's the original, 370,000 old oil from the production line..