Based upon the battery box dimensions without the slide that PC gave me, you can fit 2 of the lifeline 6V 300Ahr batteries in.Good to know. I am still not certain what batteries PC puts in the coach but whatever it is I'm living with them for awhile no matter what. I think by the time I need replacements Lithium prices will have come down to something not too unreasonable.
Or possibly I can find room for a lithium pack inside the coach. Lots of projects, so little time.