Anyone seen them, super bright but I'm trying to figure out if it's just a bulb or if I would need to get the whole Tail light assembly. Can't seem to find a Cadillac Parts Diagram online.

IIRC they are completely integrated tail lights, there isn't a bulb of any sort you can pull out.

Damn that sucks gonna have to just go with those SMT LED Towers from Autolumination then

What year STS?

The new ones