Got it out with the help from a shop. It was secured in with 4 bolts that were attached to a metal frame. I was able to get the top 2 bolts off from the access panels on either side of the TV but I was stumped after that. The shop apparently ended up taking down the rear part of the cab headliner to get access to the bottom 2 bolts.
Looks like a 32" will fit in quite nicely, a new TV will likely weigh about 1/2 of the Jensen so the industrial strenght frame will be replaced as well.
I'm considering replacing the RCA audio unit, wondering if anyone has swapped theirs out?
Straycat2161 I'll try sending you a PM.