I'll partially agree with papakb.
Unless you are taking your truck into the middle of nowhere with no cell reception, and a dead battery might be the difference between life and death, and you're running everything off the batteries without the truck running (things like radios, lights, entertainment, kitchen sink, etc) then the 6tl reserve capacity is more than you really need.
The main reason the military uses the 6tl in the HMMWV is because they use it in pretty much everything else, and it simplifies the supply chain.
the flooded lead acid 6tl is something like 650CCA rated. Pretty much any battery with a higher CCA rating than that, and has at least halfway decent reserve capacity (for dealing with the glow plugs mostly) is more than enough to operate one of these trucks. (if it doesn't have enough capacity though, you risk destroying the start box)
I think it was RetiredWarHorses that said he's even seen trucks come in with a pair of lawnmower batteries in them to start them. Might work in warm weather, but definitely not recommended if where you live gets cold.
If you are staying in cellular phone range and not going crazy off roading, then a pair of 24 series or similar batteries will work for starting the truck.
The only actual advantage of the 6tl series that I can find is the vent caps are rated for being submerged 5 feet under water. So if you aren't actually driving with water over the level of the batteries that's a moot point anyway.
Spend the extra money on an AAA RV+ plan so if something bad really does happen you can get the truck towed home.
