I havent done one in a while, and what a pain it was on my truck. The two toughest ones on the drivers side (#2 and #4, worked through wheel well) crumbled apart as i tried to remove them, the other 2 were fine. They were so bad, that pieces of them fell into the rocker carrier and i had to remove the high pressure oil rail and almost an injector to get to the broken pieces. So, what should have been a 15 min job (only was going to replace 1 glow plug) turned into a 2-3 hour ordeal between trying to remove the broken harnesses and removing the oil rail. What a royal pain.