I've replaced a lot of parts using Mac's Antique Auto Parts. But they didn't have the stainless steel trim or tail lights. I have a 55 Merc Monterey that I'm restoring - also a 4 door. Ended up buying a second one for $700 to get the fender, trim, radiator, bumpers, and tail lights. Mind you, no one seems to sell those parts besides people who have assortments of original parts and NOS (new old stock) that they're selling through eBay or forums like these. I figure in another 5-10 years, someone will start manufacturing them again. You can also get many of these parts off of a 55 Merc Montclair 2 or 4 door. And I know the fenders and headlight bezels/fender extensions are the same on the 56s. Hope this helps!