When should I change the the belts on a 2004 ford mustang?
First of all, your 2004 Mustang does NOT have a timing belt. It has a timing CHAIN or CHAINS depending on whether it has the V6 or V8 engines. This does not require replacement at any specified interval unless it has failed, which is rarely if ever. As for the drive belt, replace it only when you start to see age cracks appear, otherwise leave it alone. Hope this helps.