speedo gears

Drive gear Yes. Driven gear No. You want to change the driven gear. You will need a 23 tooth speedo gear Not clear why you want to change the drive gear unless you are looking for extreme accuracy..

Try

I didn't know if my '91 5.0L AOD had a 7 or 8 tooth drive gear, so I asked the mechanic to pull the existing factory speedo gear and tell me what color it was. I had bought three speedo gears from my local FoMoCo dealer, all close fits to what the Steeda page told me. When he said "gray", I knew I had an 8 tooth drive and had him install the 3.27s and the purple 21 tooth driven gear, then returned the unused speedo gears for credit. I do a -lot- of highway driving and the 3.27s and engine RPM were happy with this combination.

To confirm the correct driven gear, borrow a GPS and see if it agrees with your speedometer. My speedometer and GPS read within 1% of each other. (Probably the needle width and parallax error on the speedometer).

Don