That was one of the prototypes for the first fully enclosed auto racks..
I believe it became the Safe-Pac Autorack used by:
UP (Yellow w/UP initials),
WP (BCR then UP Yellow w/WP initials),
ATSF (Red then Brown),
SSW (Brown)
CPAA (Brown then Red then Yellow),
CRR/SBD/CSXT (Yellow)
NW (Black then Brown) then NS (Brown)
As far as I know, DT&I didn't get any.
Edit:
Southern Pacific confirmed but it as a different design..
and I forgot two..
FEC (Yellow)
And Autoracks for Auto-Train that replaced the Ex CN Auto-Box cars were very very similar..
DT&I was not a road known for autoracks in spite of their traffic being heavily in the automobile industry.
They did have a handfull.. Yellow with the "DT&I" bold lettering on a pannel.
Several other roads that you wouldn't expect had fully enclosed autoracks
Boston and Maine/Guilford
Illinois Central
Susquehanna
RF&P
Rock Island
Milwaukee
Seaboard
SCL
Plus a few others.. Edit..
Clinchfield
KCS
L&N
CE&I
Maybe more well known..
MKT
Frisco
Missouri Pacific
~Ian