Navy,
Unless you've got long shackles that create a flex point I wouldn't think that a panhard bar would do anything for you with parallel leaf springs, and in fact if done with Heim ends a panhard bar will actually [U]cause[U] some lateral movement of the differential on up/down travel. If your shackles are short and not thin, flimsy material I'd opt for no bar. If you feel that you need something, a Watts Link is probably a better choice.