Offers many hard to find decals, including the Missouri Pacific Eagle set used on passenger cars interchanged on the Pennsy's Penn Texas. Has issues with fulfillment; use with caution.
Shellscale offers decals for a number of roads, but notably for the Norfolk & Western passenger cars interchanged with the Pennsy.
John Frantz offers an excellent assortment of PRR decals. He also offers sets for Conrail, Western Maryland, and several other roads.