Measure the size of the TV hole, and then get a TV that fits. Ours came with a 19" Sansui, but it looks like a mouse in a train tunnel. We can go up to a 24" in ours and it seems like the Grey Wolf line uses pretty much the same entertainment centers in all the units. Keep in mind, if you already have the little triangle drop in mount, you might have to move it or change to a different style for a larger TV. They have that thing way too low for bigger screens.
TV: '06 Ram 1500 SLT QCSB Hemi 4x4
TT: '12 Grey Wolf 27BHKS
Tow Acc: Tekonsha P3 BC, Curt round bar WDH w/sway control, CIPA custom fit tow mirrors