Thank you all for the input and advice. Turns out that the yellow didn't come along untill the early 1970's.
My Layout Photos- http://s1293.photobucket.com/user/ajwarshal/library/
I think these folks would have an answer:
https://groups.yahoo.com/neo/groups/dti_modeler/info
I'm in a number of Yahoo Groups based on modeling railroads I'm interested in. The members have been extremely helpful.
Ed
I can't give a definite answer to this one, but I suspect the brighter colors were adopted after the 1950's.
When did the DT&I start using yellow paint schemes for their gondolas? Also, would it be appropriate to run a DT&I gondola with yellow lettering on a 1950's era based layout. Thanks in advance.
-Alex