Yukon Axles

When you first put it together and it tore the ends of the splines off I bet it also got the 2 sets of splines in the sure grip out of sync. When their not aligned correctly you'll never get the axle to go all the way in. You should also pull the 3rd member and clean all the metal shavings out of the sure grip (requires complete dis-assembly and don't forget that the bolts in the sure grip are left hand threads) or your asking for big trouble such as completely trashed bearings and gears.

A buddy of mine ran into this very same problem with his 72 Duster. He brought it to me and I disassembled the sure grip and cleaned out all the metal and reassembled it making sure to align the side gear splines and removed the thrust pins and put it together and it worked fine.