The first insulator I found in the field was a CD 145 B with SDP. I found it in 1971 near where I was going to college at Lamar University in Beaumont, TX. We used to have lunch at a small, wooded park about a mile from the university and not from a refinery. A railroad track ran through the park with a couple of tall poles that had a few insulators on the crossarms. Two B beehives and a couple of CD 152's embossed with No. 40 were pulled off one of the poles using an extension ladder in the back of my pickup (not the safest method, but I was a young eager collector). This is the only one I could easily find because it has been sitting on my old 1929 GE refrigerator for many years.