Vibration while driving - 2005 Dodge Magnum

check for the drive joint phasing and angle setting of the center bearing
mostly with center bearing , the drive shaft has to be split and the flange removed for the bearing replacement
the flange can be put back on in any position and that will throw out the s joint phasing
Take it to a drive line specialist shop and ash them to check the phasing and angles to eliminate the vibration
The vibration could have been from a bad joint and the new joint was not properly installed which will also vibrate
If you are not familiar with the term phasing It is when the joints are in direct line with each other when placed on a flat surface and allows the differentiating speeds of the crosses as they pass through the 90 degrees to cancel each other out and stop the vibration
the drive line specialist will know and explain it better as he will have the drive shaft to show you on

check your universal joints on the driveshaft as they will cause a bad vibration while driving

This could be the harmonic balancer or the torque converter.

Your flexplate and/or torque convertor are out of balance.
If recently replaced it should be a warranty issue.
By your testing you have determined it's transmission related.
I have seen new/rebuilt torque convertors be balanced incorrectly.

in all honesty havent a clue without a drive ,sorry

hi sramzy.
see if this link helps you out.
Vibration in car When driving at different speeds car vibrtes Google Search

Without feeling the vibration, it is hard to speculate, but, my experience here is this: you may have a bad rear wheel bearing. It is covered for 5 years/60,000 miles by Toyota

Could be motor mounts, or transmission mount. How old is this vehicle?

A vibration while driving is usually out of balance tires and a vibration while stopping is usually warped rotors. Vibrating while stopped means the idle is probably off.