Does anyone have information on when the Alpha 1 Gen II was first intorduced?

I 'm looking for a lower unit for a 1988 Wellcraft 264 Antiqua and *I
thought* that would be a plain Alpha I. I thought the Gen two wasn't
introduced until after 1990, however, I've recently seen an avertisement
for an identical model/year boat claiming it has a generation two
outdrive.

Any help in this manner is appreciated.

Bob Dimond