For the longest tume I thought my 2002 Chevy Suburban Z71 had a lifter going. The motor "clacks" when started and becomes more of a "tick" when warmed up - definitely from the drivers side. No codes, drives fine, no misses. Yesterday I noticed the top of the last exhaust manifold bolt appears to be sheared off. There is also some discoloration around that connection indicating it is leaking. I am pretty sure that is my problem. So, can that bolt be drilled out and an insert put in or do the heads have to come off? Thankfully since it is a suburban it is relatively accessible but probably more than I want to tackle on my own.