http://www.ebay.com/itm/231959192349?item=231959192349&viewitem=&vxp=mtr (http://www.ebay.com/itm/231959192349?item=231959192349&viewitem=&vxp=mtr)
That looks ancient, and small
the motor looked large to me.
I was talking of the compressor being small.. and the entire thing looks pretty old
I think it's around 54mm inducer. some were used on 5.9in ford chassis.