Smokebox Graphics decals are printed by Cartograph (same company Speedwitch uses) and are as good as anything out there.  Not an extensive line but there is also a set for Ann Arbor RR boxcars that covers everything from the 1920's single sheath cars through the steel boxcars built 1948 to 1958.  At ten bucks for a sheet that does multiple cars, I consider it to be a good bargain.  Besides the PM and AA cars there are sets for New Haven and Buffalo Creek boxcars.