The aluminum plates where just adapter plates I made to convert the 3 bolt to a 4 bolt, to attach the flange yokes.

The the vibration, just under acceleration ?
Usually the the rubber surround around the carrier bearing bad, then will be under acceleration, harder you accelerate the more stress on the driveshaft and more banging.
Usually if driveshaft is out, it is a good time to change out the wearable parts.
If you call around driveshaft shops and ask if they have the pin tool to change the u joint, then that would be everything.
Most people change out the whole driveshaft.
Can crawl underneath and just check and make sure everything is tight, and try and shake around front rear and the middle.