Found the answer:
"The slogan came into use in 1947 early in the production of the R-40-23 clones.
The first 30 or 40 of the NP cones were delivered without the slogan, while the rest were delivered with them".
About the color;
Looks like the 'North Coast Ltd'-car is a 1950 R25-clone with slightly more orangish-yellow and RED ends & blk roof.
NP might have switched from yellow on the R23's to more orange on the R25's?
The IM picture IMHO is a bit too bright, but this could be light conditions.
Later IM cars I've seen are less bright, but these could be the R25 clones w. NC slogan
I ran the prototype pictures through Photoshop and you can see #72 is brighter than the later R25 clones (the white of the Nomad logo being the reference).
That said, the PFE car at right is defenitely orange.
cheers, Fred Jansz
npin53: thanks for posting that gorgeous picture!
Ran it through Photoshop and now have my doubts about the roof being black.
Ends yes, defenitely, but roof seems red to me... compared to the black ends.