Engine vibration ?

[chopnchaneled]

OK, i've got a 68 stepside, one piece drive shaft,350 vortech engine,with power steering, 700R4 trans.

This problem just started and is getting worse. there is a harmonic or vibration that starts at 1900 rpms and gets worse the more rpms you take it
too.even buzz's the steering wheel mirrows etc.

It will do it when sitting still in park, so i'm sure it's not in the drive shaft.
I've taken all the belts off, still buzz's. checked the flex plate bolts and looked for crack's, replaced the water pump just because.
it seems to run fine, no skips.

Anybody got a suggestion? I'm kinda thinking the converter, but never had
one that was bad and i don't want to just start throwing parts at it.

Thanks in advance