We have an 05 Magnum r/t with 99k miles. The motor and transmission has been great....BUT the suspension on this thing is horrible (I loathe the man that designed it, due to the cost of upper ball joints and difficulty of maintenance). We have (in just the last few months) replaced the rear hubs, front hubs, front upper ball joints (meaning control arm), front lower ball joints, both outer tie rod ends. And while that has solved the majority of the problems I still have an annoying clunk in the front end when going over bumps occasionally (not nearly as often as I used to with the worn down ball joints and such). So I figure since I have come that far with the suspension I might as well do the sway bar bushings (look decent but have some cracking in them) and the shocks while I'm at it to finish it off.
I'm not sure about the challenger but if they have the same suspension on them that the magnum does, I'd be prepared to toss out some $ when you need to start replacing bushings and ball joints. My main complaint is that you need to replace the whole upper control arm to replace the upper ball join. Cost me $150 a side.