They say there are 2 blowers that work with this machine but 1 is unavailable. This picture is the other one. In the picture is the part number.

 

It looks like the numbers you listed are for a 3xx and 4xx, respectively,

BM27439 is the one you want, although the current available model goes by a new number and the housing is now green. The currently available model is functionally the same as BM27439.

There is also a bunch of older designs that will fit that went by several different numbers. I looked for one used for a couple years with no success. I ended up purchasing a new BM27439.

Edit to say, the current number is BM27737