Not Quite 250k But my Express 3500 HD has 236k Miles on it. It works every day of its life Loaded with tools. Ladders on top , We often have tile and some lumber / flooring loaded in the back of it with a Fork Lift. It pulls a Trailer at least weekly that is usually well loaded. The van RUNS LIKE NEW.. Its had water pump changed on it. Last year thou i had all new Oil cooler lines, Transmission seals rear engine seal and a few others . It was dripping a bit of oil so anything that was damp they replaced steam cleaned under it. I park on some Very High end driveways and cant have one Drip..
so i expect this thing to pass 250k easily.. But like all higher Mileage Vehicles you never know when something is going to happen. Always have a backup