Install one axle housing gasket then the backing plate and then the axle with another gasket between the backing plate and axle retainer between the snap ring and the axle end and then tighten the 5 retaining nuts down up wrench
It has been a while since I've install a axle so when in doubt call, contact the company you bought them from for their proper instructions scope

Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)