I'm resurrecting this thread to say...I have a 16 tooth gear in my stock 88 with the 2.73 rear end. I also have a 90 (lucky me) that was converted from AOD to 5 spd. I have heard that in 90 the drive gear was changed to 8 tooth. Needless to say, the speedo is off. I think the 90 has stock 2.73 gears matched with the old auto? How many teeth do I need on the 90 gear?