6 speed transmission resonance

[Rowe80013]

So I've searched for this and can't find anyone that has had this issue. I recently replaced the clutch/flywheel on my 99' with a Southbend Con/O and matching solid flywheel and the transmission has developed a resonance. The old clutch looked like a Luk maybe and it had a solid flywheel but I never noticed this noise before. I thought it was the rear end, but I've gone as far as removing the rear driveshaft and driving in FWD and it is exactly the same. It happens in all gears and only right at 1700 RPM when you are accelerating. I removed and reinstalled the trans crossmember thinking it might be loose or something and even crawled under the truck and had my wife lug down the engine with the brakes on to see if something was touching the trans or t-case and its not. Has anyone else experienced this? I know Southbend says that their clutch disks have no "springs" and will make a gear-rollover noise which I can hear when you lug down the engine but this is purely a resonance. She says I'm being ridicules and can't even hear it but it's driving me crazy.. Any insight would be great!

[Cj Ford]

mine makes noise too after installing the con ofe especially when your in too high of a gear for the speed .. sounds like the thing is a piece of crap and is gonna come apart.. its embarrassing at times lol