From 93 to 03 the head gaskets are pretty touchy. I don't think they were the whole problem though. You have an aluminum block, aluminum heads and steal head-bolts. I firmly believe that if you keep up with the cooling system maintenance and never let the engine overheat (I consider 240 and above overheating) the head gaskets will last forever. However, if you do overheat the engine, the aluminum and steal have different expansion rates when they heat up. The aluminum will expand more than the steal, putting a great deal of pulling force on the head bolt threads in the block. Once you've overheated once, the threads in the block are already weakened and it's only a matter of time before a leak develops. Unfortunately, there is no way to get away from these differing expansion rates. The only things that could be done were to rearrange the bolt pattern, make the threads slightly more coarse, and make the head bolts thread deeper to have a more secure hold in the block. I think the best years are actually anything that's 03 and newer; however there is a huge decline in the amount of bad HG's after 2000 simply from them rearranging the bolt pattern and changing the alloy in the block casting.