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THIS. It looks like your transmission was made on the November 20th of 1989 (or 1990 depending on what really is the last digit). From what that guy says on that website that if you fill the transmission as full as you can for the side 17 mill plug, then if it full.
I still jack the the driver side of the car when I fill the transmission. It gives me more room to work without having to take the tire off, and it is easier to get the full 2.1 qt of oil in it without having any spill on the ground. Then, when I check the fliud level after every oil change, I can do that by making sure some oil comes out, but not having to worry about transmission getting to low.