727 vibration

Since you refuse to tell us engine and car model, there were three engines that would be EXTERNAL balance. If your trans shop put in a "rebuilt" convertor, but didn't put the correct weighted one back in, it's gonna shake like a ****. Did the shop get the prop shaft installed correctly? Loose bolts/straps? Any vacuum lines disconnected? If it's a small block, did they let the distributor rest on firewall during repairs? Thus, cracking the cap or even bending the shaft?