So I was looking through my train chest and came across an old Con Cor Alco PB. I pulled it out and looked at it and thought it'd go great with my EMD F7B. I looked up the years and the PB's were manufactured starting 1946 while the F7's were manufactured starting 1949. (That seems backwards to me. It seems like the PB should have come later than the F7B.) Soooooo, who knows their history... For the Rio Grande, could it have been possible that they lashed a PB up to an F7A/F7B? The years are close enough. I put 'em together to see what they looked like and they don't look near as smooth as I'd hoped.