I have only heard rumors regarding specifically Where the 3 Tramps were found inside a "boxcar". Nothing official. I wonder if maybe that "boxcar" was actually a "passenger train car"? Again, I have never seen an 11/22/63 image of a "boxcar" anywhere inside the Rail Road Yard. And if you look at the 3 tramps photos, they are being marched down the Elm St Extension toward the TSBD. They are coming directly from the RR Yard where we see that string of Passenger Train Cars at the 8:55 mark on the National Geographic post above.