to person above.... that motor attached to that federal 4m blower is not three phase, its a single phase repulsion start motor. they were made by general electric. marathon made a similar motor years earlier that had a similar look but without the vent access and looked like a huge 3 phase motor only it has a removeable brush access cover on the rear.. to my understanding the GE motor lasted until the green cap start cap run motors in early 70s replaced them,
examples of each single phase type siren blower motor..
early 1950S to 60s, its attached to the thunderbolt head closest to ryan, has the SN compressor.
https://www.flickr.com/photos/ryanjames ... 3444088195
late 50s repulsion run, general electric hp 1ph
https://www.flickr.com/photos/ryanjames ... 3444088195
later 70s onwards cap start cap run.\
https://www.flickr.com/photos/ryanjames ... 3444088195