On one hand, I have to agree with dgce about that. It seems like that would make sense. Plus, they would probably have to develop the technical/mechanical details of getting their hardware able to put a P pickup on a body other than the PB basses.
On the other hand, I would think they might sell more basses if they have the P option available on other basses... I can't be the only one that doesn't particularly care for that PB body style. If the P/J option was available on a Bromberg 5'er, I'm not sure I would be able to keep myself from ordering one immediately!
5sg.
I think for a small up charge. They could rout a P-Pickup in any body.
A SB5000 P & J would give me gas to order one fast.

