01ws666

I've Been daling with this vibration for about a year now first looking to my driveline, then transmission for the cause then I realized the vibration is there in neutral/park also around 2500-3500rpm's so converter was replaced to a yank with no change, then noticed it looked as though my flexplate had some runout so I replaced an apparently perfectly good sfi flexplate for another sfi plate with no change in vibration... So now my cars in the trans shop for a no 4th gear issue and with the transmission out of the car they started and reved it and the vibration is still there which leaves only motor to be vibrating somehow...
So my motor is stock internals, stock balancer and pulleys. I do have prothane motor mounts and my a/c belt is removed, but the vibration didnt start right when I did the mounts as far as I can remember (its been a while) It really became noticable after I blew my rear end and twisted my driveshaft on the 1-2 shift WOT... So while I have the transmission out whats the best way to tell whats vibrating cuz I have no clue motor runs good just vibrates I'm thinking balancer somehow but for all I know it could be a crank bearing or something... Can anyone share their insight? would be greatly appreciated. P.s. sorry for the long post, thanks.