noise from rear axle?

[99Z28]

recently my montana has been squeaking when you go over a moderate to large size bump in the pavement. The squeak is from the rear suspension. The van has 84k and has the original shocks/springs in the back. It has the base suspension, not the leveling air one. I plan on replacing the shocks soon, do you think this is the issue or does something else need to be greased or replaced? Thanks!

[inafogg]

not real familiar with the montana but shocks would'nt be my 1st guess.alot of squeaks/groans are tied to a dry bushing.Good Luck