[Mike C]

Broken axles don't occur on the street much. Tire spin usually occurs long before any real stress on the axle. Avoid wheel hop at all costs though. Axles break on drag strip launches with sticky tires and clutch dumps and with the leverage from large tires and epic gearing offroad.

Disc brakes should effective retain the axle in case of breakage as well. I am practical, safety conscious, but cheap.

But I don't beat on my stuff NASCAR style either. If you really need the positive retention of the Ford style ends, go for it. But I'd move away from the truck 12 bolt as well, it is a weak link itself.