My '87 calls for ATF in the tranny, so that's what I use. Some of the trannys in these cars call for ATF, some call for gear oil. One way to tell is that if ATF is called for, there will be a pink sticker on the passenger's side of the transmission bellhousing. Also, if the drain and fill plugs on the transmission require a large allen key, then gear oil is called for. If the plugs are just hex heads that you can stick a socket on to remove, then ATF is the right oil.
For differential oil, I use Mobil 1 synthetic. I don't remember the weight.