James, I took some pix while at a salvage yard today. I used the title caption to label each picture.

If this is what yours looks like...what you are referring to as the back collar is actually a piece of the carrier bearing that came loose and froze to the propshaft. It needs to be cut off carefully to replace the carrier bearing. On this one, the carrier bearing was so bad that I couldn't get it to budge either, so it would also have to be carefully cut off. Use an angle grinder for the heavy work, remove what you can in pieces, then switch to a Dremel and chisel for the finesse work when you get close to the shaft. Working around the front collar will probably present a challenge to avoid cutting into it. Just be careful and you should be fine.

http://s844.photobucket.com/user/ma...2449_zpsfuhlsppk.jpg.html?sort=3&o=2

Hope this helps,

Matt