The main frequencies for GSP are 154.680, 154.800, 154.905 & 154.935. In various metropolitan areas, GSP has the ability to work off of those TRS's (i.e. Atlanta). The lo-band frequencies listed haven't been used in decades.
GSP. statewide is still using the same two VHF freq's they have been using for the past several decades, with the exception of Metro Atlanta.
ALL troopers, statewide, carry 700/800Mhz portables which TX back to their car and then are sent into the VHF radio which TX's at 110 watts. It is indeed the same 765.43750 @ 156.7 PL for every trooper.
The reason for this is so troopers can use the portable to talk on local trunked systems depending on where they are working, and so troopers temporarily called to metro Atlanta don't have to have an expensive 800Mhz mobile installed in their car, they just use their portable.
Also GEMA has the capability to set up P25 conventional mobile repeaters at the scene of disaster or large event. This would allow the troopers working said event to use just their portables on the temporary repeater for communications.
Yes, I-75 from Atlanta to the state line for the most part was a real traffic jam after Christmas. It as mainly due to the sheer volume of cars, there were no major wrecks that evening.
Also, all GSP units are outfitted with mobile data terminals and live GPS tracking.