Answers: I dont recomend mip centers or axles. I believe a new flm chassi comes with a rear steel dogbone if not I think they sell the right one for that application. Stock outer axles will work with hb diffs but you need the adaptor installed in the diffs so the axles will bolt up.
http://www.rc-monster.com/proddetail...ffshaft&cat=47 or you can use a traxxas stub axle and cut it too work. If you run traxxas cvd's the cups that come with the diff might work (you need to research this though because I am not sure) If you run steel centers with hb lightning diff you need 2 8mm cups and 2 6mm cups. Realize you will need the flm hybrid bulks also for the hb diffs. edit the rear dogbone is good it will work fine.