Scratchings on US first pressing:
Side 1: G81004M1-A-15B 32a JGS
Side 2: G81004M1-B-15A 32a JGS
And those aren't typos above - side 1 really is 15B, and side 2 really is 15A! JGS seem to be the initials of mastering engineer Jim Sintetos at K-Disc.
I don't know what the details on later pressings are, just that they are different to the above!
There are two different mixes of this album. The first mix was delivered quickly to Motown in order to meet the release deadline, and this constitutes the US first pressing. Teena did some further tweaking and delivered a second mix, which was used for the second and later US pressings, all the international pressings, and I believe all the CD reissues since, including the 2002 expanded edition, which is when the story of the different mixes first came to light and fans posted to one of the online Motown discussion groups that the CD was noticeably different to their LP. Easiest way to tell the original US LP's apart is from the deadwax etchings, so I will post the details from my US first pressing later.