350,000 miles!!! I heard that the LS engine is built to last and it seem so in your case. The main issue with the engine is just replacing leaky gaskets, however the the engine internals are usually trouble free if there is no excessive wear from running the engine in low/burnt oil conditions.I have an 02 Escalade and it’s still running strong at 350,000 miles. As long as you always change oil and filters and fix things on time, it’ll never do you wrong.
The LS engines are designed to run a long time if you keep it properly lubricated and fix leaks quickly. The same concept apply to the differentials and transfercase as well.