The one I listed uses dip switches and accepts the signal coming directly out of the VSS and I suspect the output of many different control systems. We are using a US Shift controller to drive the sensor and using their VSS out to drive the box. Only a few buck more than the other unit...
To keep the mechanical speedo, you need a driver. I just installed one of these on a '72. https://www.moderndriveline.com/shop/electric-to-mechanical-speedo-converter-with-58-screw-on-connector/
The linkage on the 4L80 is further back than the TH350/TH400. For the '72 we just had to move...
You could use stepside latch pins. Just one side would deter most people.
https://www.lmctruck.com/body-components/bed-tailgate/cc-hidden-tailgate-latch-kit
Noted. I'll get those books and start there. I'll start collecting parts and I'll likely have a shop take care of the bushings. The 4L60 sizing tool was wishful thinking that they were the same as the 4L80.
If you're willing and the truck has it, I need both the driver and passenger side front headliner trim and the one all the way in the back. You have my paypal info. I'll keep my phone on me. Send me a request for money and I'll pay it on the spot so you're not out anything. Then we can figure...
Damn. Jam the original motor back in it and that's a drivetrain and chassis. That'll need so much work that it'd be better to drop a new body on it. Sell it all together so the firewall can stay with the frame.
Not good at all. Regulator is toast. Probably reading that 14.2 at the battery due to resistance from all that heat. Throw a new alternator at it and check for other crusties.
If you're feeling froggy, you could wing a new rectifier and regulator at it.