Yes they do. If they are the standard size any national auto parts store can get a set. OEM
is available from dodge at about twice the price. If you want bigger ones you going need to check with a vendor like HHP, Speed Logix or maybe Steve White's a dodge dealer that does a lot of after market stuff). Be prepared for sticker shock though for high horse power axle set, last time I checked over $1000.
DSS makes a Level 5 1400 HP axle for the 226 Rear Diff. This is something I intend to step up too, as I just had my axles out, and thing I'm on borrowed time. If yo do take your axles out, do yourself a favor and replace the hub bolts. I stripped one of mine. I'm not sure how I'm going to get it out to replace. But that is a problem for another thread.