Tom,
Be sure to note the cable connections/routing. If you have a battery cut off switch for the chassis batteries, use it to disconnect the batteries. If not, no problem. You won't lose any memory, etc when having the chassis 12v disconnected for a short time. Most of the "memory"functions are powered by the house batteries in any case and are protected from loss by internal batteries or use of flash memory that stores info even when power is removed. The engine ECU and Silverleaf are powered by the chassis batteries and their memories are protected against power loss.
Be sure to clean the cables of any corrosion before reattaching. I use NAPA's spray-on corrosion remover followed by their terminal protectant but most auto parts stores carry various brands.
Not sure of the amp hour needs of your coach. I normally use a Group 31 battery. Interstate is popular but I've seen others recommended here in other threads on batteries. My coach needs 1000 CCA but yours may not require that much. If you got good service out of the existing batteries, consider sticking with that brand/rating.
Steve
