It appears to me that the train in question can be seen on the triple underpass in the Volkland photo taken from Stemmons Freeway immediately after the assassination. I put a red arrow and wrote the red words on this copy of the photo.

I have done some quick line of sight alignments with some of the buildings and approximated Volkland’s position. It appears to me that the train cars designated by the arrow are on the triple underpass. Please feel free to double check my alignments for yourselves. Please let me know if you disagree or agree with my assessment. Thanks!