George,
Five year old house batteries that have been properly maintained may very well have at least two or three years of life left in them. I have seen properly maintained house batteries that were ten years old and still functioning properly, although at a diminished capacity. So replacing the house batteries just because they are 5 years old is not normally a recommended procedure unless they are giving you a problem.
As for a replacement option in your area, I do not know. However if you are going to be at one of the FMCA rallies, there will be enough battery sales companies there to ensure you enough options on type and price as well as knowledgeable installation personnel.
Gerald
