I ordered one of these and should be receiving it tomorrow:
http://www.grizzlyindustrial.com/pro...e-Chrome/H5642
It should be a direct bolt-in. I am replacing the Fender style bridge on my new SX Jazz bass, not to improve the sound, but to upgrade the bridge mechanically. I have never liked the cheap Fender style bridges because the saddles slide sideways all the time. This new bridge has slots to keep the saddles lined up.
I'll post my opinion of the Grizzly bridge after I get it installed. If I like it, I'll order another for my P-bass.