My Car has a terrible shake that needs to be fixed, but im having trouble understanding where its coming from.

its not a bent rim, bought new ones.
replaced my driveshaft mid-bearing.
and tightended it all down, but it has a shake between 10-20 mph, and like 40-50 mph, the shifter nob goes wild and it feels as if the entire tranny is bouncing. my steering wheel also feels the jitters. any advice?

when i tighten the bracket holding the mid bearing on the driveshaft it seems to help it a little, but it unloosens over time from shaking

sounds like ujoints