@Stircrayzy
Just so I'm sure that I'm understanding you correctly, you replaced one of the actuator motors on your transfer case (There are 2 of them an upper & a lower actuator motor) and that solved your problem, of not being able to shift into reverse??
If that's correct, that doesn't make sense to me at all.
Maybe a voltage issue from that actuator motor as you suggested (some of those wires do look rusty) but, that's definitely strange.
At face value, I really don't see how your T-Case actuator motor, should have any effect on your ability to shift into reverse, when all the transfer case does, is shift you into & out of, different modes of 4WD.
Definitely see a lot of rust underneath there.