I'm trying to find where the reverse light switch plugs into the harness. Anyone have any info or pics.

 

A/T: Backup lamps work thru neutral safety switch, located (1973/77) at the bottom of the steering column under the dash.

3 M/T: Backup lamp switch located on steering column under hood, adjacent to 1st/reverse selector lever.

4 M/T: Backup lamp switch threads into shift tower.

 

And a pic is worth a 1000 words. Here is some discussion about back up lights.

Whenthe trucks came with a manual trans, there was a dummy plug used tobypass the NSS switch. I've never been able to come up with a partnumber for the dummy plug. To bypass the automatic set up:Unplugthe switch and discard or ignore. There are four wires in the harnessplug, two each, red w/ blue trace and black w/ red trace. Run ajumper between the red/blue and red/blue, do the same for theblack/red.Thatcompletely bypasses the NSS switch. Your truck will now startandthe back-up lights will be permanently on.Now onto the backup lights.
Inthe engine compartment is a little U shaped jumper wire. It'll belocated on the drivers side splash pan, just in front of the firewallwhere the wiring harness comes through.Unplugthe little jumper, this will shut off the back up lights. Thereshould be a back up light switch on the trans cover. Run two wiresfrom the switch to the two wires that were jumped. This will get yourback up lights working again.
Justa note, you could make a jumper plug out of the NSS. Cut the switchoff the harness and splice the two pairs of wires. I just hate to cutthese switches up. New, they're getting pricey.Here'sthe little jumper in the engine compartment. EDIT:If you don't care about the back up lights, just jumper the red w/blue trace wires. This will by pass the NSS but the back up lightswon't work.

 

Your 4th picture down helped, reverse lights working now. Thanks

 

Glad to hear you got them fixed. I am sure I got that pic from ND anyway, I know the top one came from him and mikeo0o0o0 provided the 3rd one.