Our house batteries are grp 27, unknown brand or Ah rating.
Meet a Vegas owner with a 25.2 and theirs were grp 24 same unknown brand.
So if you have no space between the 2 battiers they are most likely grp 27.
If there is plenty of room then my guess would be grp 24.
The batteries in your coach should be from World Wide Battery Company, the model number It shows in the system is 27D-170. Hope that helps. This is from Thor on axis 25.3. Two batteries.
Ours are marked D27DC - 160 which doesn't tell us anything other then grp size. If and this is a big if the -160 is reserve cranking then they are maybe 85 to 90 Ah batteries which is pretty pitiful for coach like this.