Transmission swap

Hi and thanks for using 2CarPros.

The transmissions could have both been the 700R4 transmission. If that is the case, confirm that all connections, sensors, harnesses, and everything appears the same. It should work. However, I can't guarantee it. We only recommend direct fit parts. When you change years, anything could be different.

There were two different transmission used in 1989. They are the following:

3L80/3L80HD (400/475) Automatic Transmission
4L60 (700-R4) Automatic Transmission

To identify the one you have, see pictures 1 and 2 for identification tag information. On the 700R4, trans-axle identification information is found stamped into the case pan rail

Picture 1 is the 3L80 and picture 2 is the 4L60 (700R4)
_______________________________________

Let me know if you have other questions.

Take care,

Joe