Yes, it's a little confusing. The hand edited specs for 72-73 show a change from coal to oil. It is my understanding that they were delivered as oil burners, but it's quite possible that they were operated as coal burners for a short time as indicated [Charlie, have you got any of those coal burning 72-73 pics?]. The fuel conversion between coal and oil was fairly simple and bunker oil would be easy for the WP&YR to get, so I'm guessing they started experimenting with oil burning in the late 40s, used up their coal stocks and gradually converted the mainline locomotives so that by 51-52 they were all oil burning as JD True says. Of course he also states on that same page 28 that 192 was the only 190 class converted to oil, yet we've seen photographs with oil tenders behind 190. JD's book was published in 1994 from letters he had written over the years, and he admits that his memories of the details were fading when he wrote it all down.