Holy Cow!!!
Robert,
The 305 is not all that common, it was in its day the *cheap* cleaner, bare bones no frills model, selling new for $49.95, +$$$ for tools.
The 305 was interestinng because they were made from stamped metal, spot-welded together instead of the cast aluminum that the regular models were made from.
However research has revealed that 305's were made from both the stamped metal and cast aluminum.
Yours looks to be all original, down to the cord. Very nice.
I am at Michael's at the moment, when I get home I can post the serial numbers and production dates, so we can see where this one falls in the mix.
The 305 was made 1940-1042, with a handful more made in 1945 as the war was ending.
Hope this helps some
JP