1997 Pontiac Transport replacing therostat

Roughly twice as long as on any other vehicle. Just the procedure with no testing before or after can take as little as five minutes on some vehicles, 15 minutes on most cars, and up to half an hour on the difficult ones. Yours is a really miserable vehicle to work on. Expect about an hour or so. By the time the coolant is added, the air is burped out, and the mess is cleaned up, you can add another half hour.