It was taken in Portland, OR in the mid 80's. At this spot in the yard, there was always different engines there, when ever I came to photograph trains. So I really don't know if they were putting them out of service or not. If I'm not mistaken, if you look at some of the other photo's that I uploaded last night, you will see that there is several different road numbers of the same type of engine.
I'd need to dig out my slides. My last time seeing a C636, was, I believe February, 1981. There was at least one, plus some U-Boats parked in the old yard behind Hoyt Street. They were placarded for shipping to Australia. I believe it was to Hamersley Iron Pty, Ltd. A couple had vagrants living in the cabs. Boxcab E50