The one on left is the 2000 series, the one on the right the 4000 series. All of the digits after four reflect options - single product single hose, single product dual hose, dual product, suction pump, dispenser, etc. All of the Bennett id numbers carry the details of the design and there are dozens of different configurations (I am the Bennett dealer for central NC). 2000 series is from mid-1950s to late 1960s, 3000 series from 1959 or so through mid 1970s, 4000 series from 1964-2005 and still in common use. Current production models available both mechanical and electronic display are called the 3K series and reuse the 3XXX series numbers.
3000 and 4000 series config numbers
XX12 single single dispenser
XX13 single single suction
XX22 two product dispenser
XX24 single product two hose dispenser
XX25 two product suction
XX27 single product two hose suction
Note non retail (gallons only) version of the 4000 series is the 3900 series. Suffix digits still apply.
Wayne Henderson
Petroleum Collectibles Monthly
Kernersville, NC
