How do I reinstal the automatic axle shaft ?

The front Subaru axles are held on to the differential splines with a roll pin. The splines and shaft need to be aligned properly on reassemble for the axle to fit properly. Is it the inner tripod joint that came apart? If so the inner CV joint needs to have the rubber boot removed to ensure the joint is reassembled correctly, reassemble the CV boot and replace the band clamp.