Before Faball was bought out by the Wonders family, the original owner J.P Fabinich, was making a small amount of bowling balls. These were NOT Hammers, merely called Faballs, after the owners name.
I thought I had heard that the ones he was making were just polyester balls, but anything is possible I suppose, and this ball could be from that "pre-hammer" era.
Definitely something worth checking into.