I got this from Chris Trunk who is team leader on making the two frameless tank cars operational.
"The only NG tank cars that were ever lettered 'Gramps' were the frameless 'Van Dyke' UTLX tank cars. Not all the NG frameless cars were Gramps, only about 20 were, and there were also about 10-15 plain (non Gramps) UTLX frameless NG tank cars in the fleet. Both the narrow frame and the frameless cars were leased to the Hughes operation and both styles can be seen in older photos taken of the Chama oil loading dock. In later years mostly only the frameless cars were left in service on the DRGW, with many of the narrow frame cars having gone to the White Pass or scrapped.
The original UTLX Van Dyke SG frameless cars were built in two series, class 'V' and class 'VV', the original class 'V' cars in 1908-1909, and the later class 'VV' from 1911-1912. The main distinguishing difference is in the brake set-up. The class 'V' has the type KC brake with the cylinder and reservoir connected as one single unit, while the class 'VV' has the KD brake where the cylinder and reservoir are individually mounted and connected to each other with a short length of pipe.
We, (the CATS) currently have two of the original class 'V' tank cars, 11036, (non Gramps), and the 11037 (Gramps), and the one of the class 'VV' cars, 11050 (Gramps- the one purchased from Ashby). I hope this clears up any questions. Chris"
Chris also said to ask any questions he may have missed.