Well how about a rundown on previous maintenance so we know whats been done or not, only reason I ask is plugs are due at 100k. So either they have been done or need to be. If you have typical hand tools and aren't a total tool yourself then it's pretty damn easy to do. However there are other things that may need to be done as well, tcase fluid, front and rear diff, cooling system flush, fuel filter, trans service, IMO if your plugs are working I would be more worried about stuff that will leave you stranded if neglected long enough, then do plugs if they wern't done at 100k.