So I need a 22 tooth and a 6 tooth. SHI*! My car is at the shop and ready for pick up tomorrow for my gear change. Dam, i was sure all I needed was a 20 tooth. I was told that by about 30 people. You are talking about an 89 5 spd? GRRRR

 

20 tooth isnt close for 3:73. 6 tooth and 22 tooth is what you need. you can only get close with a 7 and 23.

 

That's just the best route to go is all I'm saying, it's a lot of work to replace the drive gear, probably cost $100 in labour. You need to know what gear you have in your tranny to start with, either the yellow 7-tooth or the green 8-tooth

Just think about it.

Stock rear-end gears 2.73

Stock speedo drive gear 7

Stock speed driven gear 19

19 / 7 = 2.71 (the rear-end ratio)

NOW

23 / 7 = 3.29 (not even good enough for 3.55's, but it's all you can get)

 

I have a 90. I think 89 and lower the 23 tooth is for 4.10's..... There was a chart on D&D performance's website.

 

Here ya go guys. THis is also from 50resto.com, latemodelrestoration.com.

Speedometer Gear Help Guide

Ring & Pinion Speedo Gear Part Number
1983-89 Mustang Manual 5-Speed
3.08 18 Tooth LRS-17271H
3.27 19 Tooth LRS-17271A
3.55 20 Tooth LRS-17271B
3.73 21 Tooth LRS-17271C
4.10 23 Tooth LRS-17271D

1990-93 Mustang Manual 5-Speed
3.08 20 Tooth LRS-17271B
3.27 21 Tooth LRS-17271C
3.55 23 Tooth LRS-17271D

1984-89 Mustang Automatic AOD
3.27 19 Tooth LRS-17271E
3.55 20 Tooth LRS-17271F
3.73 21 Tooth LRS-17271G
4.10 23 Tooth LRS-17271J

1990-93 Mustang Automatic AOD
2.73 19 Tooth LRS-17271E
3.08 20 Tooth LRS-17271F
3.27 21 Tooth LRS-17271G
3.55 23 Tooth LRS-17271J

1996-98 Mustang Cobra Manual 5-Speed
3.27 19 Tooth LRS-17271A
3.55 20 Tooth LRS-17271B
3.73 21 Tooth LRS-17271C
4.10 23 Tooth LRS-17271D

1994-98 Mustang Manual 5-Speed
Except 1996-98 Cobra
3.08 20 Tooth LRS-17271B
3.27 21 Tooth LRS-17271C
3.55 23 Tooth LRS-17271D

1994-98 Mustang Automatic AOD
2.73 19 Tooth LRS-17271E
3.08 20 Tooth LRS-17271F
3.27 21 Tooth LRS-17271G
3.55 23 Tooth LRS-17271J