I haven't done this on an AMC but did this on a Mustang.  If the AMC is similar its not that hard.  Remove the rear drum, flip it around and loosely
 attach it back on the axle, then pull on the drum to pull the axle out.  On the Mustang the bearings are pressed on so you'll have to go to a machine shop to get the new ones pressed on but I think the cost for the bearings and pressing them on should be in the range of $50-75.  You may want to replace the seals also but that is also pretty easy.  Slide the axles back in.  
   
  This is working from memory from about 6-7 years ago on a Mustang.  You may need to pull the backing plate for the brakes off but even if you need to do that I believe you can leave the brake shoes, springs, etc in place.  However, if you have it all apart and haven't serviced the brakes for awhile it might be a good time to do that also.  Good luck.
 
  
  Dave
  72 Gremlin X
        I have a 77 hornet amx with the 258/4 speed. I was told that the rear 
axle bearings need to be replaced. My questions are: 
1. Is this difficult, or can I do this myself (I'm somewhat of a
 
novice)? 
2. What other rear axles (amc or otherwise) will either directly bolt 
in or will bolt in with minimal modification? 
3. Does anybody have 1 for sale around the Chicago area? 
4. My mechanic says it will be $850 for the parts/labor. I've never 
had this done before - is this a reasonable price? 
Thanks, 
Dan