I used a Valvoline semisynthetic. It's a little lest costly than full synthetic and comes in convenient squeeze bottles. This allows you to change it without a pump; you just shimmy up underneath the car and squeeze the new oil in.
If you buy gear oil in cans, you'll need some kind of pump to get it in.
hassman: 85W-140, isn't that a little thick? Doesn't the rear end normally take 80-90W.
What else, '73 MB 280 SEL (Lt Blue)
Daily driver: '84 190D 2.2 5 spd.