O Scale Railroad Sign/Marker Decal Sheets by Impko. Each sheet measures approximately 3.125" x 4.5". From what I can tell, this particular batch is likely from the 1970's. They're untrimmed, bright, clean, crisp, flat, and don't show any signs of ever being exposed to moisture. If you've worked with old decals, you know that sometimes they don't survive when soaked in water. Experienced modelers know to use a clearcoat or something related to help with the process, and it's possible (maybe even likely) you'd need to do that here.
$3.00 for two sheets shipped. $1 for each additional sheet. (I have a bunch.)
PayPal, check, money order or even a few singles in the mail accepted.
E-mail me at papertrw@aol.com with your interest. Thanks for looking!