Hello all ...as Stephen ..pointed out ...International ..... ....below your Pacific from their 1952 catalog .....
scale ???? International pieces vary with which kitchen table they were made on .. the box cabs they made are big ok call it 17/64ths ..or just big ... most the steamers I've seen all seem to be closer to 1/4" .... but quality does vary ....(greatly) .... I have two International Challengers ......one well it looks like International ...the other wow ...this builder must have been one the hand selected to go on to Max Gray (KTM) stuff ...both runs just fine .... but International noted that the Challenger just special order .... above their normal pieces ....their Swallow is quite nicely done also .....
International is certainly an interesting page in early O scale ...
below also photos of the two Challengers .... original price $225.00 ...big bucks at the time... ..you can see from the photos ... no way the same person built both engines ...one was building International pieces for a living ...and the other builder had real talent and went somewhere in the model train world
Cheers Carey