Did D&RGW have 36' Boxcars?

I'm modeling 30's-40's Colorado NG in 1:20.3 scale and I'm going to dual gauge a portion of my layout with some 1:20.3 scale Standard Gauge rolling stock. I think the perspective of a few pieces of SG cars will be really great looking to set off the NG.
The first piece of SG is a 36' boxcar kit which was based on a Tenn. Southern RR 36' boxcar. I'm trying to figure out the lettering for it and hope this forum's can help. I'd like to letter the boxcar in D&RG either the old style lettering or flying Rio Grande. I'm trying to stay true to the prototype or at least reasonably exhaust the possibilities.
Did D&RG have 36' standard gauge boxcars, and how would they have been lettered? And, what numbering for the car?
If my question is inappropriate, strictly speaking, for this forum, please accept my apologies and I will withdraw it.
Thanks in advance for any and all help.