Yeah, the Phat Cat is basically their soapbar P-90 fitted into a casing that'll fit into a humbucker-sized slot. Probably their classic P-90. That's how come it simply slipped into the bridge of the Ibanez (same size humbucker slot). The soapbars are like $5 less (list). They make three or four models-- a classic sounding one, a hotter one, a custom, etc.
Here's a link to their site.
Products - Seymour Duncan/Basslines