I have a '91 LX 5.0 and I have a ticking noise coming from the drivers side head or lifter area. It is really kind of hard for the to destinguish the differnence because they are so close in procimity. I took the valve covers off to make sure all was good and all the rockers are still torqued to 24 foot pounds. I am thinking it is either one of two things. Either it is a bad guide in my Trick Flow heads (pedestal mount so it is a common problem) or it might be a lifter. I had the heads checked out befor I put them on and they had 2 bad guides which I had replaced. The heads only have like 4000 miles on them since then. My question is, what cause a lifter to tick? I have had someone tell me that I might need to switch oil filters to see if that helps. I will definitely try it but what do you guys think?