| 1 | YSMX | Panama Gypsum Co. | added 1/1962; 7/1965-1/1975; eliminated 4/1976 | | NAKINA |
| 2 | YSMX | Canadian Gypsum Co., Ltd. | added 4/1976; 1/1980; eliminated 4/1991 | | NAKINA |
| 3 | YSMX | Panama Gypsum Co. | added 1/62; 7/65-1/75; eliminated 4/76 | | NRHS |
| 4 | YSMX | Canadian Gypsum Co., Ltd. | added 4/76; 1/80; eliminated 4/91 | | NRHS |
| 5 | YSMX | RETIRED09-29-92 ATP (1676) [CANADIAN GYPSUM CO. LTD.; PANAMA GYPSUM CO.] | | | PWRC |
| 6 | YSMX | Canadian Gypsum | | | RSRV |
