Can anyone identify if this piece of hardware, and if it is part of the 72 challenger door glass assembly? I only have one and not sure if this is needed... Thanks in advance for your help.

I believe this helps keep the glass tight against the weather seals in the frame

I don't have a 72 Challenger anymore but I checked my 71 Challenger and that piece was not in the door. It looked like a stop for the window. I checked my 74 Charger door and it is definitely an up stop for the door glass. I checked my door parts from Challengers I've parted out including a couple 72's and I have a few of the stops that look like your picture.. I know you wanted a response from someone with a 72 Challenger but it's used in the 74 Chargers.
Terry

Usually the window anti-rattlers had the fuzzy material on them. The stops I have in my Charger have the material or block on the end made of rubber that is slipped on the end and its bent at about 30- 45 degrees from the main flat part. I can go look at a friends 72 Challenger this weekend possibly.

I just replaced my door glass.
That is the window stop. There is 2 off them, 1 at front 1 at rear.

They limit the upward movement of the glass.

I'm pretty sure they are used in all year challengers. Here's my 74 and you can see the part. It does what was mentioned above, it keepss the glass from rattling.

My 73 didn't use the bracket with the rubber on it. The up stops are just solid metal brackets that bolt to the inner door frame. The up stops that attach to the glass are just plastic tubes that come into contact with the metal brackets on the door frame.

Thanks all! Judging by the responses I am leaning towards that this belongs on a B-body.

So. afetr seeing a few of these posts, I looked closer inside the door of my 71 Challenger and these stops are installed in the door and have the rubber on the end. Used in both e bodies and b bodies.
Terry