I spent a number of days installing a solid rear axle on my trike including a new disk set up and all, only to cut it in half before starting the bike. Have you tried to push that assembled unit around your driveway or garage yet? It won't work and won't turn at all. One wheels spin will be fighting the other and you'll drive the ped right into the curb. Especially since that rear end is as wide as it is. Needs a differential.