I'm working on my '65 Cornet 500 and I'm wondering about the arm rest bases. Were they chrome from the factory. Mine appear to be chrome on the inside but on the outside they have gray paint over the chrome. Not sure if someone painted them a long time ago or if the factory did that?

I have a set of bases from a Coronet 440 that appear to have a little chrome left on them but most of it is worn away. Here is a picture of the two side by side.

I also see that the Coronet 440 interior red is different than the Coronet 500 red. The 440 red is darker than the 500 red. I guess I wasn't aware of that before.

Yup, flash-plated chrome bases.
Color & trim selector looks like the same red on vinyl, though the 500 also had that darker accent. Sunlight faded that color pretty effectively. Those 2 armrest pads do look different, but that detail isn't shown in the selector. I'm inclined to bet on age & UV exposure, but I could be wrong.

The '65 Parts book shows a different color code for 500 models than the 440 models. I don't have a color code book with color panels in it but the codes are different.

Check out the Hamtramck Historical site. Go to Library, then Color & Trim Selector, then 1965, then Dodge icon, obviously choose Coronet.
P4R and H1R (500 & 440 interior codes, respectively) refer to trim level, not color, which is the R. P = Premium, H = High. The 4 and 1 most likely refer to buckets vs bench.
Similar to how interiors were coded on the later cars.

Chrome. ABC Moparts has a good reproduction of them.

https://abcmoparts.com/products/64-65-a-b-c-body-front-arp-base

The arm rest bases in my '65 Coronet 500 were chrome plated but painted grey. Not sure when they got painted but it must have been a long time ago. I pulled bases from a '65 Coronet 440 and they appear to be chrome although most of the chrome is long gone.

I think I also figured out the red color. The pads from a 440 are a darker red than the pads from a 500. So it looks like Dodge used a different red color for the premium car. I confirmed the two red colors with a restoration guy who gave me samples of the two materials. He didn't know it was 440 vs. 500, he just knew that some customers need the brighter red and others need the darker red.

The 440 would use a dark maroon pad because that has two tone door panel and it would match the center section which is maroon. The 500 is a solid red panel through the middle thus using the red arm pad.

Thanks Dante, that makes sense. It seems that Dodge used these two red colors back and forth on the different models.

I've looked at the dash pad a few times and I think it matches the red arm rest pads but it is hard to tell. I don't think the dash pad was the dark maroon, but it doesn't seem to be red either. Could just be the effect of sun over time.