I have a '97 F150 and I was having trouble with the front hubs locking. I removed the axle from the truck and discovered that the plastic slippers on the fork assembly in the axle were broken not allowing the passenger side drive shaft to lock in. But as usually you have to buy the whole fork assemble from ford(about $160) because they dont sell the little plastic slippers. The question I have is that the axle shafts slip very easily on the differential while I rotate the drive shaft flang. Is this normal or do I need to replace the ring gear on it?? Thanks, Tony NY