If you can get a decent 2.73 rear axle for cheap (which I can't see being too hard), swapping out an entire axle is something you could do in a day in your driveway. Bribe a trustworthy friend with beer and pizza, and you're in business. Of course, I say trustworthy, because you don't need an axle dropped on your skull.
As for shift points, is it an electronically controlled transmission? If it isn't, it's probably not too hard to adjust, as it would all be mechanical adjustments. Again, something you could do in the driveway.
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