As I recall, that's when GM tried the infamous two piece lifter body with a hardened disc on the face fused to a lower hardness body. After a VERY short time period the lifter face would take out the camshaft. For a while there it seemed every 305 under the sun was back at the dealership for a camshaft change. What I always found curious is that under warranty the engine was never dissembled or cleaned when the cam was replaced. And the warrantied engines seemed to run fine after that. I had two friends with Chevy pickups that had this done under warranty.
