I manage a fleet of 15 Chevy cargo vans for the company I work for. They are in what I would say very hard service. 50-70k miles/year, Stop and go, heavy loads, generally beat on by drivers. They are mostly 4.3L 1500's with a few
25-3500's mixed in. They usually are beat to death by about 160k miles. Most frequent problems I see are multiple bad trannies per van, usually after 100k miles and fuel pumps. I'm confident that a van driven by a responsible person and maintained well should have no problem reaching at least 200k miles.
On another note there are a few older style chevy vans in the junkyard I frequent that have well over 435k miles on them. Cant imagine trying to drive a van with that many miles.