Recap:
88' C1500, 305 TBI, TH400, 170,XXX miles.Lifters were noisy as all hell the first 5 or so cold starts after an oil change. Lifter noise would only go away if the truck was physically shut off and then restarted. After the first 5 starts lifters were perfectly quiet. The issue presented itself only after switching from Mobil 1 to AC Delco oil filters.
Update:
Changed the oil a few days back and used a Purolator PureOne filter. Absolutely ZERO lifter noise after the first two cold starts. So, what I have is a GMC that doesn't like Delco filters..................he he he he.
Thought those who responded to the OP might be interested....................
Doc