A/T - 125/440 T4 Sprocket and Final Drive Identification
TECHNICAL BULLETIN # 120DATE: July 92
TRANSMISSION: 125/440 T4
SUBJECT: Drive Train Ratios
APPLICATION: GM
125/440 T4 Sprocket and Final Drive ID
If you have a car with a 125 or a 440 T4, and you're not sure that the sprockets or final drive are correct for the vehicle, you can use the Regular Production Option (RPO) label to find out.
The RPO label is a sticker that shows what options were installed on the car. Figure 1.
The RPO label is usually located on the trunk lid or the spare tire cover. Two exceptions are the Seville which is found on the left rear door jam and the Fiero which is found on the front right fender well.
Once you've found the RPO label look for a code that begins with an "F" or "G". These codes describe suspension options on the car. (Axle ratio, type of shocks, sway bars etc.) Find a code that matches one in the chart).