Grinding noise while 4wd is engaged

[Bullet4x4]

Yesterday, I noticed that there was an occasional grinding noise while 4h and 4l was engaged while going up my muddy driveway. I heard the grinding noise a few times and then the noise went away. Today I engaged 4wd in the same spot only to hear a constant grinding noise and a lack of 4wd engagement. It only did this for a couple of seconds before going back to 2H. After carefully navigating the mud in 2wd and getting home, I inspected the transfer case and front driveshaft (np208 on 88 K5, stock axles). While turning the driveshaft exiting the transfer case by hand, it was freely spinning inside the slip joint attached to the front axle. I haven't worked on this before, but I am assuming this is the problem.

Does anyone know the best way to go about this repair? Do I need to replace the entire front shaft, or could the front sllip joint be repaired? What is a reasonable price for this repair? Thank you for your advice

 

[Blue85]

So you stripped the splines in the front driveshaft? Is the truck lifted? If so, it might need a longer shaft and this problem was at least partly due to that. You have about 3 options:

1. Find another used shaft. Somebody here might have one. Good luck in junkyards - every one I've found has loose splines.
2. Have a shop rebuild your shaft. Not a bad option if your C/V joint is in good shape. Shop around as prices vary. It will be cheaper if the stock tube can be re-used (i.e. shaft length is fine).
3. Order a new shaft. May not be much more $$ than option 2. Again, shop around.

For either option 2 or 3, you can go for a longer slip spline. This is nice not just for super flexy suspensions, but the longer engagement is also more durable and holds the balance longer.

 

[Bullet4x4]

Thank you for your response. The truck is at factory ride height on 33x10.5x15 inch tires. I haven't disassembled the unit yet due to a lack of free time so far. Is it possible that the splines are in good shape, but the slip joint has become worn?