Looks like the screw is missing... It might be just rusted and stuck... Try something like WD-40 on it, wiggle it around and see if it will push out from the back...
1954 Chevy 3104 3 Window Hydra-Matic in my family for over 60 Years
Once in a while you get shown the light in the strangest of places if you look at it right... "Scarlet Begonias" Grateful Dead 1974
