Most are inside the bell housing, top right corner. (starter side)
You'll see a 2 wire lead coming from inside there kinda toward the front of the trans where it meets the bellhousing.
Check for shorts too, as mabe you'll get lucky and be able to fix it with a bit of wire rather than a trans drop.
Also, on some models which year(s) evade me right now, there's also a switch in or near the shift tower. (literally two switches, as brought to you by the department of redundancy redundancy department)
Does yours have it? Dunno, mabe. :shrug:
If so, then you can eliminate the wiring for the one in bell housing one and work with the much easier to deal with tower version. (make sure yours is that type before getting all happy with the wire cutters or whatever though)
Just a thought; did you do any "alterations around the 3 contact trunk lid switch? The contact side on the trunk body rim can be reinstalled 180 degrees out of phase.
I recall sometime ago that this mistake made a change to how the brake lights worked, don't recall if it affected the reverse....
worth a check.
To see if the reverse switch is "shorted" you should be able to check this at the switch connections from the tranny with an ohm meter or continuity tester. If shorted, I'd just disconnect it and go with no reverse lights, till I had a good reason to do tranny work...