Buying older ISX truck for cash vs "fleet maintained" newer ISX

[Sledge]

Possibility of being better off to pay cash for a ISX with high miles and have it worked on right away... Versus buying a low mile ISX that may already be infected with problems.

Just reading/watching on lot on the ISX. Companies doing things like extended oil drains, screwing around with water temp sensors, bad or none existent engine/emission maintenance, wrong settings for engine model put in by a dealership, etc.

Just kindof makes me thing that while no guarantee of anything, it could be smarter to pay cash for a higher mileage truck, and have in-frame/overhaul, @m*m^2'd, etc. From that point I guess it would be about putting the rest of the truck's components (clutches, axle spindles, etc) on a replacement schedule and going from there.

btw i have about $33,000 (CAD) saved up now that i could probably buy a low-tier truck with. I'm pretty good at hitting phone books and auctions. I like the idea of having a paid-for truck, and owing my bank some in-frame money.

This would be my first truck.