gtx supercharged

I just bought myself 2 04 GTX Supercharged, 1 - 114 hrs, 1 - 130 hrs. Brand new aluminum trailer. Paid 7000 for everything. They both seem to run great. I have a 96 XP that was great for many years but is now in need of scrapping, so I know what the old upkeep was but I am trying to figure out...