[Rick_L]

The 700-R4 transmission was renamed to 4L60 for the 1992 models. They are essentially the same transmission.

But, beginning in 1994, Chevy started using 4L60E transmissions. The 4L60E is an electronically controlled version of the 700-R4/4L60. The 4L60E needs an electronic controller to run it - so it's not interchangeable.

700-R4 and 4L60 transmissions have a TV cable that connects to the carb or throttle body, and have a 4 pin connector for the torque converter lockup. The 4L60E transmissions have a 23 pin connector for the controller, and no cable.

 

[Rick_L]

They started using the auxiliary valve body in 1988. Some of the warranty replacements from 1987 had them too. Best bet is to avoid anything older than 1988.