There's a product called, "Joe's Model Trains- paint and decal remover"
It's a slow acting paint stripper, that usually needs several applications, and removals to completely strip lettering. It doesn't remove the base color!( at least not in the lettering removal process, if you leave it on long enough it will soften and remove base color). I've used it, removed black lettering from Athearn reefers, and am very satisfied with the results.
Pete