I'm really confused now, though - if your problem is a bent axle housing, why on earth are you buying thirds? Man, the quality of advice we can offer is predicated entirely on the accuracy of the info you're providing.
My suggestion for you at this point would be to have your truck towed home, return both thirds you bought, and start surfing junkyards until you find a truck with the same axle code as yours. Buy the axle complete with third, brakes, everything. Rent a shop crane and Home Depot truck to get it to your house and unloaded, pull your old axle, and replace it with your new one.
Checking car-part.com, axle housings hub to hub appear to go for $500-$600 in your area, and a used 4.10 third will probably be another $100. You'll probably pay less through craiglist, but at this point I don't think you should be spending any more money on unverified parts.
You can pull your old axle and install the new one in a day. You'll save on mechanics costs, and educate yourself regarding your truck at the same time. Worry about lockers and new gear ratios later, just get a new axle and get your truck back on the road.