The following information can be useful if you plan to build a Rio Grande layout and wants to know what era to model. All information is from:
http://www.drgw.net/info/pmwiki.php?n=Main.Diesel
But I sorted it a little to make it easier to see what era is the most interesting era for me (and others) to model. Enjoy!
1940 - 1949
38-43 GE 44-ton 1941-1964
66-74 Baldwin VO660 1941-1968
100 EMD NW2 1941-1968
101-119 Alco S-2 1941-1966
120-123 F-M H-10-44 1948-1968
150-152 F-M H-15-44 1948-1966
540-551 [A-D] EMD FT 1942-1950
552-554 [A-D] EMD F3 1946-1950
555-557 [A-D] EMD F5 1948-1950
558-564 [A-D] EMD F7 1949-1950
600-601 [A-C] Alco PA 1947-1950
1950 - 1959
38-43 GE 44-ton 1941-1964
66-74 Baldwin VO660 1941-1968
100 EMD NW2 1941-1968
101-119 Alco S-2 1941-1966
120-123 F-M H-10-44 1948-1968
150-152 F-M H-15-44 1948-1966
540-551 [A-D] EMD FT 1942-1950
552-554 [A-D] EMD F3 1946-1950
555-557 [A-D] EMD F5 1948-1950
558-564 [A-D] EMD F7 1949-1950
600-601 [A-C] Alco PA 1947-1950
5100-5113 EMD GP7 1950-1972
5200-5204 Alco RS3 1951-1966
5300-5304 EMD SD7 1953-1991
5305-5314 EMD SD9 1957-1992
5401-5514 EMD FT 1950-1965
5521-5544 EMD F3 1950-1966
5551-5574 EMD F5 1950-1970
5581-5764 EMD F7 1950-1968
5753-5774 EMD F9 1955-1996
5901-5954 EMD GP9 1955-1991
6001-6013 Alco PA 1950-1967
1960 - 1969
38-43 GE 44-ton 1941-1964
50 Dav 30-ton 1963-Present
66-74 Baldwin VO660 1941-1968
100 EMD NW2 1941-1968
101-119 Alco S-2 1941-1966
120-123 F-M H-10-44 1948-1968
130-139 EMD