Have any of you experince any vibration after the swap?

I have a vibration from 3200 to 4200rpms or 55mph to 70mph
i have unbolted the converter and the vibration went away and when im driving down the highway and i can throw it in neutral and its still there so i know its not in the drivshaft or rear end, the converter is a new JW 10" but the fly wheel is still the original fly wheel
So i think im going to try to change the fly wheel to see if it makes a diffrence maybe when its bolted up to the converter it is week and to flexable

What do you think?

 

I have the same problem, but I think mine is the driveshaft. Stockies are known for that. Let me know what you come up with.