Interestin...Whats the deal with the just " weld it up?"
You weld the spider gears in the differential to create a spool. It is known as a lincoln locker. It would be completely locked all the time and pretty awful to drive on the street, but it would be perfect for your ranch. I would make sure someone who really knows what they're doing welds it up (or just do it yourself). If done right, a welded diff is pretty reliable.