The paper bag/blower kit
I bought one of the kits to use paper dirt bags inside the cloth bag. The exhaust then comes through a round port on the converter and in to the paper bag. Removing the two bags you could use the dirt devil as a hand held blower. I think in later models this feature was built in. I know they moved the hose inlet port from the front of the motor where you access the belt, to the top of the nozzle.
They didn't move the opening where you could access the belt and hook the hose,sorry, they changed the diameter of the hose to a narrower size that fits on top of the nozzle with a narrower hose opening.
By mid nineties they had gone from one speed 2 amp motor to two speeds and a 3 amp motor. The early models came in three colors, red, red, and red.