Originally, the D3A still had the Eureka-made R-1024 (type G) power nozzle as an option, for the first six months of D3 production/sale. Then (October 1980), Rexair replaced that with its own design, model R-1650 (type A).
In late 1981, the PN receptacle changed from a 3-wire design to a 2-wire design, but the main hookup to the wall outlet was still 3-wire. This model was known as the D3C, with the power nozzle becoming model R-1650 (type C).
~Ben