Changed plugs last night and started it up and let it warm up. Everything sounded fine and I turned it off. Was going to go for a drive today when I heard this noise shortly after starting it up. Has good oil pressure and can't see any metal on the end of dipstick but noise sounds kind of deep to me. Eyeballed a couple of the torque converter bolts and they look good. The engine is idling around 700RPMs.