Found the problem or lack thereof after 8 hours of wrenching. Turns out it was the slip tube on my passenger header vibrating....



72 RR, Pump gas 440, 452s, 3800 lbs, Corked, ET Radials,. 11.33@117.72. Same car, bone stock 346s, 9.5 comp, baby solid. 12.24@110.