You'll need to move a few wires around and add two wires straight to the PCM for the input speed sensor on the 80E (which the 60Es did not have). Info on the trans plug side can be found in this link, but ignore the pinout info for the PCM. They're talking about the newer LS PCMs. To find out what connector/pins you'll need to add wires to at your PCM you'll need a factory service manual with the pinouts for your specific connectors.
https://sites.google.com/site/sloppywiki/everything-ls/4l80e-info
If you're not comfortable with moving the wires around at the plug yourself, or just want to simplify the process, Nelson Performance makes a 60E to 80E wiring conversion kit that simply plugs into your existing 4L60E harness and moves the necessary wires in a little 6" additional section of harness. They also include an input speed sensor harness with the wiring and pins necessary to run that to your PCM. I used their kit on my red '97 C1500 when I 80E swapped it and it worked great.
http://www.nelsonperformance.com/?page_id=850
I have a thread on that '97 C1500 60E to 80E swap here if you're looking for more info. You'll have to deal with some things I didn't due to the fact that your truck is 4WD, though.
https://www.gmt400.com/threads/97-c1500-4l60e-to-4l80e-swap.38819/