heres the deal. 4wd does not work. when it is engaged and hubs are locked, front tires can spin, the 1/2 shafts can spin (opposite of each other), but drive shaft will NOT spin. its a 86 4runner sr5 turbo with manual conversion. i was wheelin around in 4H and 4L just fine not noticing the problem, until i got stuck and saw only rear wheels were turnin. can anyone help? advice is much appreciated. thanks