We have a 1998 Sienna with 135,000 miles on it. Its still in one piece, running well...until this week. It failed inspection (leaking exhaust, engine mounts missing) & then started to overheat. Turns out the radiator is leaking, too. Our mechanic says it needs a new exhaust system -- including catalytic converter--new radiator, thermostat & flush & engine mounts. Total: $2600. Is is worth it or is everything else going to fall apart, too? What is the life expectancy of the engine? The transmission? The chassis? We only drive this car about 3000 miles a year now.