Roy, the Boler/Scamp/Casita axles are normally welded on (I think Casita
may now be bolting theirs on, but am not sure), not bolted on. I recommend you consult with your axle guys to see if they can weld on the bracket that Dexter sells and then bolt the axle to the bracket -- If you then ever need to change your axle again, you could do it yourself.
If you don't get brakes
(ordering axle with brakes
equipped is least expensive way to get brakes), be sure to at least have the axle equipped with brake flanges (about $3!!!) -- Without the flanges welded on at the factory before the rubber goes in, it's not possible to add brakes.