Look for a set of good door panels for a 59 Belvedere. Can be any color.
Mark H.
Mark, someone might have an old set but SMS Auto Interiors reproduces them if you can’t fin them here. I have bought a Sport Fury set and they are good. Plan on waiting 3 to 4 months for them if you order them now.
Post some pictures of your Belvy in the show your ride section of the Forum when you get a chance. If you have already, then I apologize for not remembering … 
John Q.
Along with naming the model (Belvedere), you should also specify 2HT, 4HT, 4Sed, or whatever..
Door panels back in the day had backing made of a sort of hardboard, which is hydroscopic. Finding decent used panels is certainly a challenge, although not impossible.
My local upholsterer used 1/8" lauan (aka “door skin”) for the backing on my car’s panels. Lauan plywood holds up well over time.
I don’t know what SMS uses, and their prices and their delivery time can be painful. If you are not looking for “factory-original” in regards to your door panels, I suggest you check with your local auto upholstery company 
your right, I forgot to mention how many doors. It is a 4 door sedan. I will get some pictures up as soon as can. She on jack stands right now getting new trans lines. My old door panels are really old and brittle and are cracking. Also one of the panels was cut off at the bottom. My guess is it suffered water damage.
Mark.
Perhaps BigM in California will be able to help you.
Do you want all four door panels to be the same color? 
I will try Big M. You never know. Yes I would like them to be the same color.
So, not like my sock collection…