Construction details, Union Pacific B-50-42 boxcars, UP 105100-106099

Mark Heiden

Hello everyone,

I'm looking for some construction details regarding the Union Pacific boxcars in class B-50-42, series UP 105100-106099. According to a table in the November, 1990 issue of RMJ, these cars were built by American Car and Foundry in April, 1951. A photo of UP 105238 is available at:

What I'd like to know is:

1) The cars were equipped with either Apex Tri-Lock or Transco running boards, 500 cars each. What was the breakdown by car numbers?

2) A modeling question: Has anyone tried adapting Plano 207, a Transco running board kit for Santa Fe reefers, for boxcars? Some photos of this part are available at:

3) What trucks were these cars equipped with? From the photos I have, I can't decide what type they are.

4) What brand of hand brakes were these cars built with? The table in RMJ lists Union and Universal, but for only 100 and 150 cars respectively.

5) Did ACF use the same welded underframe that Union Pacific was using on it's home-built boxcars of the same period?

6)There appears to be a Royal Type F brake regulator just ahead of the left-hand truck in the picture of UP 105238. Was the entire order built with these?

Any and all help is greatly appreciated.

Mark Heiden

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