One problem related to coolant leaking has been reported for the 2003 Chevrolet Suburban. The most recently reported issues are listed below.
2003 chevy Suburban 1500 4wd 5. 3l gm has a known issue with the heads on these vehicles with the 5. 3l engines. The company (castech) who made the heads let them go with a defect that allows coolant to leak into the motor. Gm has a TSB on it as well #06-06-01-019b it can cause possible overheating due to coolant loss, as it leaks into the engine it creates rough idle and a slight missfire which will damage the converter sometime in the future. They know about this defect and should be forced to replace these heads with different ones. The only way to correct this issue is to replace the heads with another company.