Hi Phil,
Here is a collection of Fender bass bridges that should fit your J bass.
http://www.guitarpartsresource.com/b...uinefender.htm I would expect the 5-screw, 4-saddle bridges to fit.
Other notable choices include the Leo Quan Badass II and Gotoh 201.
The webpage is merely to show what's available. You may (or may not) get better prices at another dealer.
One important note, DON'T THROW THE ORIGINAL BRIDGE AWAY! It may be valuable/important one day.
Good Luck
Bob