4l80e not shifting, no speedo

[Cabnchassis]

Parked my 91 to swap the doors out for a power set and do a little work on the glow plug wiring. Everything went as I would expect but when I put the dash all back together and ran the truck it wont shift gears and my speedo stopped working. I changed the output speed sensor and there was no result. Before I throw anymore parts at it I'd like to just make sure I'm barking up the right tree. Can anyone give me a troubleshooting process to follow, to identify my problem? I'd really appreciate any help.

I also noticed that the wires from the output sensor had been repaired in the past near the trans, is there any reason not to re-run them from sensor all the way to pcm to just ensure they do what they're supposed to?

Edit to add: the truck is an R model so it's a square body and has a square body gauge cluster if it matters.