Harmonic pulsation / Vibration?????????

I still dont think that any exhaust system will cause a physical vibration or harmonic. (understanding that "harmonic" can apply to a sound wave or a physical vibration wave)

Yes, I have a "drone" at certain rpms.......in fact I have that in my durango with an aftermarket exhaust too to some degree.

But actual physical vibration I think has to be a mechanical concern.....engine or drivetrain, wheels, etc.

i am still searching for a cause for my harmonic vibration (mechanical shake)...starts at about 40 mph and is gone by 50. I feel it in the whole car including the steering wheel....front end was rebuilt and the convertor is correct, new balancer, etc.

i would love to believe its "just" my exhaust, but I really dont think it is. If it were the exhaust, the vibration would be felt at rest at the same rpm........and I have an exhaust that is pretty popular on e-bodies (magnaflow, x pipe) and I have not seen anyone else with the same exhaust on an ebody complain of the vibration....there are so many of these exhausts out there, I doubt highly that a vibration like mine would go unaddressed by the buying public and magnaflow if it were in fact the exhaust causing it.

I am wondering if my driveshaft needs balanced.

Or it could simply be that my engine has this "quirk" as someone else put it due to someone rebuilding it etc....I dont know the history of my engine other than it has had a cam, heads, intake and carb replaced.....