Hey guys I have a 2003 Chevy 2500 HD with a 6.0 and it makes a weird ticking noise while under a load sometimes when reved high in neutral I have replaced the manifold gaskets, had manifolds re surfaced, replaced broken studs and noise sounds like it's coming from bottom of the motor almost like a ticking pingy noise while accelerating from a stop mostly, I don't hear it when I'm up to speed sometimes when I shift from reverse to drive I'll hear it ping quickly for a few seconds then stop. Any ideas what this could be. Truck is clean, greased and oil is changed frequently. Currently running valvoline 5 30 full synthetic. There is no vibration or mechanical sensations to go along with the sound just the ping ping ping when taking off.