Engine noise in 92 Park Ave. Ultra w/SC - HELP!!

[hartbeat]

Need help in determining what is causing the engine noise in my 92 Park Ultra w/sc. The noise sounds like shaking a tin can of marbles. It is most evident from the passenger seat and appears to be emitting thru the exhaust manifold. The engine has 72K miles. The SC was replaced about 4,000 miles ago. The noise is not always there. The power is still good, especially when you wind it out. A trip to the local Monro garage told me the problem was with the piston rods/bearings. I can't believe this because the car runs too good. Please help analyze. Thank you.....

[deadring]

err i'd go for the balancer shaft?

anyone?

[parkavenuechrome]

You seem to be beating the $hit out of your PA, Take it easy, Could be anything, timing chain, rod bearings, cam bearings. Get it checked, check your oil pressure, my bet is your harming the motor reving it like that all the time, especially being a PA, If you wanna do that, have the right oils, lucas oil stabalizer is nice, and make sure you keep the temps down. I have installed a 180 degree thermo. does wonders. Mine isn't a SC, but I wind it up now and again, but i am freek when it comes to motors and oil so I take care of them way to well. also make sure your CAT converter isn't blown, it would sound like marbles. Remeber is a 3000+Lbs car.