blazer engine vibration

Got a 93 Blazer with a 4.3 vortec. when the truck is in park, neutral, or even while driving, you give it gas, and when the engine hits im guessing around 2000rpm it vibrates the truck, any higher and the vibration goes away, and at idle it dosent vibrate. i took the inspection cover off and watched the flywheel and it dosent appear to be vibrating, i also manually turned it over to inspect for cracking and it dosent look like it is. the crankshaft pulley seems to be on fine also. any suggestions on what to check would be appriciated.

The harmonic balancer can cause this too but i dunno if the 4.3 had them in 93.

did you check the motor mounts?

You didn't mention whether or not this thing has been apart?? The torgue converter and flywheel are balance units with weights attached, if the torque converter has been disconnected it may not have been put back in the same relationship to the flywheel...Try removing the bolts and turning the converter one set of holes....you may have to try this twice to get it right..if it hasn't been apart,,the damper could be the problem..

went through everything one more time and decided to take the transmission and transfer out, i ended up finding a cracked flywheel right in the center, where the flywheel bolts to the crankshaft, you cant see with the torque converter on. ended up taking about 8 hours total. thnx for the advice