74 van problem after trans swap

just had a rebuilt trans installed. not the trans that came out but an extra that i had. they used the same torque converter. now i have a vibration. when you rev in neutral right right when you first step on the gas and cruising at forty mph. the trans shifts fine. of course the mechanic says he doesnt know what it might be.
any suggestions?

I'm thinking the mounts might be shot on that new trans? I don't know how they are mounted in the vans but maybe the mounts were shot?

chances are, they didn't align the torque converter before it was removed. Torque converters are balanced to the input shaft and if they aren't put back in the same position that they came out, you will get vibrations.

thanks guys,
i put the old mount in and it cured the problem.
i apprcieate your response



chances are, they didn't align the torque converter before it was removed. Torque converters are balanced to the input shaft and if they aren't put back in the same position that they came out, you will get vibrations.