What were the eras or system areas that the 3 Walthers PRR N6b caboose paint & lettering schemes represent? (Also, if "close" to accurate.)

Walthers #932-7651, etc.

1-Roman Lettering & bars.-"red" cupola-black roof.
2-Keystone at top.-grey cupola & roof.
3-Keystone in middle.-black cupola & roof.

I believe I saw these cabooses in the Chicago, Ill. area in the early 60's, but don't remember their schemes.

Didn't find this info in a search of this group's postings.

I want to get some for the Chicago area circa 1947.

Thanks, Paul Hillman