I am stumped, how do you remove the driver side 1983 Fairmont taillight housing?

The lens is busted and it is different from the driver side taillight lens and housing?????

Looks like someone installed a completely different year or maybe it is the right year and the driver side is the wrong year??????

Anyway I removed all the retaining nuts that protrude through the back side of the housing into the trunk yet the taillight housing will not budge??

Any ideas??

JUST snagged this coupe for $1100.00 has 53xxx miles on it (original)
already getting the ball rolling to install a 351W with a C4

thanks in advance
Mike