GEN IV 4L65 Info
Some, and I say "some" GEN IV engines came with the 4L65/70 transmissions in 2007-2009. Most of the GEN IV / 4L65 combinations where in the cars and smaller SUV's like the Envoy & Trailblazer. In this configuration the TCM (transmission control module) is a separate computer and attached to the main harness. It is referred to as the T42 TCM and will run either the 4L65 or 4L80 transmissions. If you want or need to use these transmissions the earlier GEN IV engines that came with the 4L65/70 can safe you money since we can modify the OEM harness keeping cost down. Subsequently, if you want to run the 6L80 on these earlier engines will require a new harness and added cost.
By 2010 I believe just about all Truck / SUV applications got the fully electronic 6L80 tranmission, and in later years updated versions of it. To use the 4L65/70 or 4L80 on the 2010+ engines will require a new engine harness and adds cost.
All engines on the GEN IV Engines For Sale page will show available options and pricing.