well.... I spoke to Odyssey Batteries and they said that the 34R would indeed be the better choice over what their book calls for, a group 48 (not a 91).
one battery is made here in the usa and the other in the uk. they said that the usa (34R) battery was made differently than the uk batter and something about how it is manufactured is what makes it a better battery choice anyway.
good to know thanks. My 13 has the 91 from the factory and the 48 is right out of the odyssey fitment guide.
mine was weak on the second night on the trail. the fridge wasn't set too low but the ambient temp got a little low that night - enough to cause a no start. fortunately I have a stick and parked pointing down. not much runway before plowing into other jeeps or tents I had one shot.
That is some good info as I have found out the batteries between my vehicles will interchange. I have a 97 Ranger Splash 4X and since winter when I left the wife drive my Rubicon she will no longer get out of the drivers seat.
A regular group 34 fits as well. A little massaging of the harness was all that was required. I think i removed 1 or 2 factory zip ties and rerouted the ground and it fit no problem. I have a sears die hard platinum and for whatever reason they dont offer a 34r. My Arb cooler put a serious hurt on that garbage battery from the factory.