Long story, but my cousin has a crane business and had three Hummer H3s in 2016 she replaced with Silverados for her fleet. She sold one H3 to Carmax with like 310K on it (5 cylinder one), kept one, and sold me the other, a 2008 H3 Alpha (5.3L V8) with 277K. At the time the trans/differentials had been replaced at 200K, and it had brand new tires on it, but it needed several things. Since my acquisition three years ago, I have put about 3K into it: brakes, rear main seal, fluids, tune up, and a bunch of other random things. She's at about 299K now. I really should sell it (2020 TRD Pro OTW), but I like it too much, and it's not worth anything. There will come a point where I no longer put money in it, but I enjoy seeing how long I can get it to last. However, OP, I have no plans to swap an engine or anything when it goes. Ill just find a low mileage one if I want another. Plus, it still looks and runs really good, more like a 100K than a 300K vehicle. Basically, that's a long winded way of saying keep up with your fluid changes and follow factory intervals for tune ups/filters and what not. Maybe be more conservative because of the mileage, and use synthetic fluids. Also, be nice to the tranny. No brake torquing!