I have a 87 PF. I have been having problems getting it to lock in to 4x. It has the auto hubs which I have just replaced. When trying to lock in you can hear what sounds like gears meshing but it won't lock into 4x. Occasonally it will grab but if it roles back at all, say a foot you loose the lock. The transfer appears to be working, when you put it in 4 low the gear ratio has dropped as it should. The last time it engaged, which took some work I heard a loud pop from the front end. It did however stay engaged until it was backed up. Can anyone please assist out there that may have encountered this problem. The only area I can think to look now is either in the CV's or the from differential and for you PF owners you know what a headache it is to access the differential....Please help. If it is easier to reply via e-mail please do so to mxtmanx5@aol.com Please indicate in the subject line 87 pathfinder so I don't dismiss it as spam. Thank you