Accessing Radio Connection In a 1969 Valiant

I crawled under the dash and took a shot at this yesterday. I removed the ashtray and the drop-down door it sits in that's painted the same color as the dash(Is this the hanger or the piece above it with the light connected to it?). I also tried to remove the piece with the lightbulb that is directly under the radio, between the ashtray and the radio casing. I removed the 4 screws, but couldn't wiggle it out of the opening, and didn't want to force it. I removed the two pieces of bracket hardware--the hex head screw that mounts from underneath and the phillips screw that mounts from behind with the head facing the front of the car. After doing so, I am able to move the radio up and down, but it will not slide towards the firewall at all. The only other hardware I can see are the six or so 1/4" hex heads that are screwed into the casing of the radio on the sides and back.

What's holding me back here? Is the radio screwed in on the underside of the casing, above the ash tray light? Is it the knobs? I can't see how they are preventing me from taking the radio out. I'm sure it's easier to access everything with the radio out, but all I need to get at are the wires. I'm leaving the radio in the dash and mounting my aftermarket one on the floor. The only connection I saw exposed was the antenna. Is it possible to get at the wires without pulling the radio, or am I almost there? Once again, any help is appreciated. Thanks a lot.