cat 6500 serial# AT1F50368 G TYPE other # are 6724 au2164

I doubt that replacing modules is all that cost effective. AND we would need the trucks serial number to be sure you get the correct module, not so much the module numbers.
does it have any codes on the dash?
it sounds to me like it's not so much a module problem as something else bad.
perhaps we can help you troubleshoot a little further before we go tossing parts at this truck?
I think we can get you the modules with not much problem, but at this point could not guarenty that would fix the problem, and they are not a returnable item, and do require the core returned as the core charge is about equal to the price of the module.