What Dan's talking about is a distinct possibility. I was thinking about your problem while driving to work the other morning after I posted. My 2000 Silverado pings lightly during low speed slight acceleration. My 69 C-10 pings rather badly if I don't feed it 93 octane, again mostly under slight acceleration. I wouldn't call either of these a "knock" since I have actually heard a connecting rod knock. The pinging I experience comes from multiple cylinders, so its a higher repetition rate. The rod knock repeats once per engine rev, so its much slower. If you actually are hearing a rod knocking, Dellman, then I fear there's no easy way out.

If its making the noise at idle, under no load, then it almost assuredly not pinging.

regards,
Leon