At the risk of being wrong, I thought I'd give this topic a shot as it's fairly old.
The decal sheet appears to have lettering for SLSF 42094. I managed to find a old 35mm slide on Flickr of SLSF 44213, which appears to be a 50' boxcar. Looks like it might have a 8 foot door. All the decals on the decal sheet appear to match those which appear on a prototype of a similar era and number.
If I was able to find all of Frisco's boxcar orders I would be able to tell a lot more definitely, but I figured I'd try some internet detective work.
Sorry if I am incorrect.
"Keep your stick on the ice" - Red Green
Yet another one for my Forum friends and this one is a bit of a challenge. I purchased a new run railcar from a model railroad company that seems to have the wrong doors for the era as shown by the dimensional data. (Won't name the company.) Anyway the referenced decal sheet was mentioned as the correct set to properly letter the doors. The set shows as also being for SLSF boxcars. As I do a smidge of SLSF as it formally merged with the BN at the very end of the era I model, I was wondering what boxcar(s) that set letters. Figured I'd try to get a sceond car out of the set if possible. As usual, thank you for any assistance that can be provided.