I think the 2080 was from 1970, and subsequent versions matched the last digit of the year: 2082 was in 1972, 2083 was in 1973.....
Each series of Eureka Williams uprights of the time had a range of models:
1970: 2010, 2040, 2060, 2080
1972: 2012, 2042, 2062, 2072, 2082
1973: 2013, 2043, 2083 (the Golden Box-Top Rugulator Cordaway version)