I was reading about the castech head cracking problem on the 4.8 and 5.3 engines. The GM bulletin lists 2001-2006 engines. Even though they didnt list it, was there any of this same issue on the 1999-2000 engines? Just wondering because i have a 1999 with the 4.8 that loses very small amounts of coolant over time and has developed a lifter that wants to tick..