What are the 4L80E transmission harness variations by year, and can they be mixed?

Here is what the documentation says. Each point links to its source; details depend on your exact computer, harness and transmission.

• The Quick 4 includes a separate input-shaft-speed-sensor connector that is used only for 4L80E applications; 4L60E/65E/70E transmissions do not use it. (US Shift)
• The 1995 4L60E received a pulse-width-modulated torque-converter-clutch solenoid; 1996-and-newer 4L60Es are not interchangeable with earlier models due to the bolt-on bellhousing and related updates; the 2001 4L65E gained a five-pinion planetary carrier, better 3-4 clutch, improved input shaft, and deeper pan. (US Shift)
• GM rates the 4L60E at 360 lb-ft of torque, and US Shift notes the transmission can handle roughly 400 to 700 horsepower depending on year and internal modifications. (US Shift)
• Pre-1993 4L80E transmissions need internal harness GM part 24200161 (or equivalent) to be compatible with the Chevrolet Performance controller harness. (Gmspecialtyvehicles)
• 1999-2002 PCMs use blue/red connectors while 2003+ use blue/green connectors, but the transmission-swap pin locations are the same. (Uploads)

Confirm against the instructions for your exact parts before wiring. More: Transmission control in our tuning guide.