Just changed my transmission oil today. I used 2 blitz rhino ramps to lift up the front wheels then I used 2 jack stands to lift up the back wheels (4 point lift). I got underneath the Z very easily with that set up.
I also used measuring buckets to make sure I was putting in the right amount transmission oil (3 quarts).
Similar to these (can be found in paint section at home improvement stores, I got mine at LOWES for $2.50):
Shifting does feel smoother throughout however I can really feel the difference going into 1st and 2nd gear the most.
Thanks again Spearfish!