Thanks, everything seems to spec then. As I said startup voltage is about 14.6 to 14.8, then drops to about 13.6 after a few minutes at idle. Cruising on the highway at 2,500-3000rpm voltage stayed around 13.6 to 13.8 (had scanner hooked up while driving). Resting voltage with the truck off showed 12.6.
Cleaned and coated terminals with dielectric grease, tightened them up good and just threw my little 1 amp automatic battery maintainer on there for good measure. Also changed my cameras so they are not on when the truck is not. They never drained the battery (at least not enough to ever cause it not to start) because they barely use any power but again, just in case.
We will see if the problem re-occurs. I've had this issue on other old cars but like I said, in 12 years it's never happened on the ranger.