Ok, I read Sloan, whew!

There is a WHOLE lot in Sloan's book about the tank cars, but unfortunately not much about their disposition.
One thing, it looks like thoese 10 Texaco cars in the picture are on their way off the narrow gauge in July of 1950.
I can't reproduce all that is in the book (would violate the copywrite), but here are a few notes:
Most (except the Teaco) narrow gauge cars were built or converted in Alamosa. There were 60 to 66 UTLX's, of which 28 were leased by Gramps (the frameless ones). Texaco had 10 early cars then 10 later cars from 1937 to 1950. Conoco had 46 cars (first lettered COLX then CONX) and they traveled on the D&RGW, RGS and (believe it Rick Steele) the C&S. Many went to Gunnison via the RGS. In 1929 a closure on the RGS meant that all had to use the Valley Line to Salida. This was the main reason for the new K-37's were assigned to Salida until about 1950.
And as far As I can tell, there were only two refineries on the Narrow Gauge D&RGW. The Conoco plant in Farmington and the Oriental plant in Alamosa (there was an early one in Florence).
P.S. Just got a copy of the May Trains. Haven't read it all yet, but my first impression is that the title says: "...Volunteers Rescue a Narrow-Gauge Railroad" buth there are no pictures of any volunteers! And it should have said "...rescued...AGAIN."