sometimes for these reasons a local CV / driveshaft ' shop ' rebuilding YOUR OWN ....WYSIWYG beats returning the core ,the car's original hard-part for some "Mystery Reman " , ya know
95% convenience these days , I know

After all that...it was the first thing I replaced. Drivers side CV. Turns out the aftermarket replacements do cause problems. Installed the used original CV's...problem gone.

He showed me what he meant by "not pushing back" if you compress the original CV's, the tripod will spring back, the aftermarket ones don't, they just bottom out and stay there. Apparently, that causes the vibration.