hi. I have a 1993 Pontiac Formula LT-1 with 6-speed T-56. I changed the rear gears to a 3.73 and the speedometer registers to high. How can this be fixed? Some say a gear installed in the trans or can the PROM be adjusted??
Thanks BL

I had a 93 and can tell you that a few had 700R4's in them. Mine did. Most are 4L60's. I may be wrong but I think the 93 is the only 4th gen with a removable chip in the ECM. If so you can swap it out. Anything else requires reflashing the ECM.