Rear Diff Problems

I have a 489 cone style that has bottomed out in the case real bad. There is etch marks in the metal and all. I am looking for a power lock clutch style or an Auburn gear style diff. Has anyone had any experience repairing/replacing one of these? Or does anyone have a refinished 8 3/4 diff with 3:55 or 3:91 gears in it they would like to sell?? any help will be appreciated.

-340dartswinger