2nd Tim’s recommendation to replace the axle housing yourself. I’ve done it, due to rust causing a leak, and it’s not that bad. Do axle seals and rear brakes while your in there. There’s too many issues with trying to replace the back cover. When you cut off the old cover, all the metal shavings and rust flakes are going directly into the gears. Also, getting to good enough metal to weld to may be difficult. If you decide to do it yourself, I’ve got a rust free housing. PM me if interested.
Here’s my before:
And after all replaced: