Rodeo, 2000, 3.2L V6: At 1800-2000 RPMs there is a rattle in the exhaust system. It sounds like a lose heat shield, but the truck has been up on a lift to check heat shields and none are lose. When driving with another person and the passenger wondow open (the passenger can really hear the rattle), it seems to be from the area of the cat converter or a vibration in the passenger floor. Also when tapping the exhust pipe around the cat converter it sounds as if something is lose or free inside the cat converter. A mechnic has suggested that the front exhaust pipes maybe double wall construction and the inner wall has broken free from the mounting point and is vibrating.
Note: Mileage is 98K