Have the "rack n pinion" replaced at the dealer first. Fix brakes later at local mechanics. The dealer most likely exaggerate the issues. Front brakes on Dodge Grand Caravan are of disc types, while the rear ones are of drum types. They are servicable, especially the rear ones. You can diagnose it yourself to determine if the chatter is caused by the "rack n pinion", or the brakes or both.
A Grand Caravan with 40k is very young. Mine has 165k and still works like a new one. You don't want to get rid of it unless you have issues of transmission or engine.
Good luck with yours!
Alex
