Thanks, Longbox! The more I think about it, the more I think this snapped bolt is going to cost me an entire diff replacement. I can get a Colorado diff for $400. I may have found a carrier on ebay for $150+$20 shipping+$135 for seals and installation kit+$120 for an axle=$425.
Does anyone have the total width of an original axle, measuring from the wheel mounting surfaces? I don't have a bed on now and I don't want to take a route that will make more work for me later.