Thanks for the response guys.... I'm working nites so I'm just waking up. I have a new flex plate and yes it made the noise before the header install. A little history.... I rebuilt the front end and engine several years ago. I'm running the stock pistons, rods, and crank. I had the block line honed so that I can install ARP main studs. I installed a 204/214 elderbrock cam kit and double roller timing set. I broke the engine in using Lucus brake in oil, the engine has 80psi oil pressure @ start up, 50-60 psi while driving and 20-23 psi hot @ idle. I have a Terry Houston Down Pipe and a Hooker Catback exhaust with Aerochamber Mufflers... Here's the strange part.....I do not hearthe noise @ idle or reving the motor in park, reverse or neutral, if I foot brake it and build boost the metallic ticking starts sometimes not everytime. If I place jack stands under the rear axles and apply the emergency brake and press the brake petal tring to build boost it will not make the noise. The noise only starts when driving and the rpm's are between 1200 and up and it sort of follows the engine rpm but it is not steady. Once the noise starts if I slide it in neutral while keeping the the rpm's the same the noise will stop,put it back in drive and it comes back. I have since replaced the cam with an Erson 208/208 flat tappet with Johnson lifters with the same results. Sorry for the long post!!