Page 2 of the Jan. 1964 issue of the MR magazine
See:
The boxcar, tank car, flat car and caboose were copies of Athearn. The gondola was from Rivarossi or Roco. According to my research, these five products were passed on to AHM and then to Bachmann in 1971. The models below are modified. See my blog posts. 4683
The blue is a late Athearn blue box (modified). The crown boxcar (original) looks just like the very early Athearn.
I think “OK” is a Hong Kong mold manufacturer.