LondonGT

Heyall I am new to the mustang world and got my self a 90 GT, I am currently replacing my cats for E -test and got a BBK X pipe with cats, I also got 2 new oem O2 sensor, will this still need the mil eliminator to have normal functioning? or since I am still using stock O2's are they not required?

second the car came with 373 rear end gears in a 8.8" I am currently trying to find teh right speedo gear to go with it, does any one know were to get them or what specific one i need? oh sorry its also an AOD tranny

7upedition

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

Joel5.0

MIL eliminators are for post-cat O2's, typical setup in OBD-II systems ('90 is OBD-I, post-cat O2's not used). You need the O2's connected to the system to allow close loop operation....not that it won't run OK, but they assure normal functioning.....for the speedo gear, check the table at http://www.fordracingparts.com/download/charts/142.pdf . Hope this helps.

7upedition

http://steeda.com/store/-catalog/speedometer.htm, check this out and do a search for the past 6 months on speedo gears etc. you'll find a ton of good info... good luck !

LondonGT

hey thanks for all the speedo gear help, I did some online calculations, and it says with my tier size and the fact that 90 AOD's have a 8 drive tooth I need a 23.8 to go with my 373 and 235 45 17's. so I assume 23 is the closest I can get, and thanks for the O2 help, so its just run the O2's like normal