"I got information directly from INEOS that the aux battery will be a Moll AGM 12V, 105Ah." quote from some guy in the other thread linked above.There's a photo from Greasemonkey in this thread above ~ it's not a Moll 81105 as that's an AGM type.
I do not know what it will be, I just want it sealed whatever it is. Between cars, trucks, RVs, golf carts, boats, and yachts I am over unsealed batteries. My opinion sealed last longer, I dont have to worry about something getting cooked by an over enthusiastic charger, alternator or regulator and while I have not had a vehicle that will experience the bumps, holes, jiggles and joggles like this one, I would guess that something to keep the liquid from sploshing around like Absorbent Glass Mat or Gel would be a benefit.