Microscale's set 60-228 has a very large graffiti decal for SP 171208, which they say is a 50' single door boxcar "made by Athearn", at least in HO. Looking online, the only pictures I can find for an SP boxcar in the 171200-171299 series are for SP 171242, which is clearly a combination plug/sliding door car. These pictures are from 1980. The MSD set doesn't say anything about when the graffiti was done, or what paint/lettering scheme the car had.
Were the earlier single door cars rebuilt to double door? If so, when?
Or were they replaced?
Or maybe 171208 and 171242 were from different series, and the number ranges didn't end on 00/99?
I model 1974, and have a MT car painted and lettered with this decal, but if it wasn't in service then, would just as soon have the proper type. I doubt that the original was a PS-1, and know the modern car wasn't, but that's the closest available in N scale.