Just FYI some interesting background on another group of D&RGW mill gondolas
Jim Eager wrote the following -
D&RGW 30050-30099 (1st) were built by PSC 3-44 for the Defense Plant Corp, assigned/leased to the D&RGW to handle output from the Geneva Works steel mill built north of Provo by BSC for the DPC. After the War there was a disagreement between the Gov and the railroad over the L-97 UP-design 4-6-6-4s assigned to the Grande during the War. The Grande didn't like them and wasn't going to buy them. The Gov said you don't take the locos, you don't get to keep the gons either, so they went off to the ARR in '47, along with D&RGW 50000-50449, 41 ft gons built by MtVC 10-43. The locos went to the Clinchfield, also in '47.
To replace the 65-ft mill gons the Grande ordered D&RGW 30050-30099 (2nd) from PSC, blt 10-11-48, which were almost identical to the first set, both being AAR-pattern drop-end cars like the Athearn model. The Grande didn't bother replacing the 41 ft cars, instead ordering 52 ft cars D&RGW 55000-55449, built PS 1948-49.