[MrE]

Rick, you should be able to purchase the adapter cable already made up. SilverLeaf used to sell them, but there are plenty of suppliers that sell diagnostic adapter cables. The problem when searching is verbiage, I've seen your 12-pin Molex also referred to as GM ODBI. A lot of our forum members are using the VMSpec from SilverLeaf, they can chime in on how they hooked theirs up.

This image should help;