Originally Posted by GreaseMonkey
No, only part-time. The wheel doesn't jerk at all, I just feel a clicking through the steering wheel and brake pedal.
Your '79 Chevy has full-time 4WD???
Yes, I put lockout hubs on the front to reduce the friction for highway driving. It originally came with solid hubs. When they are locked, I get wheelhop on a turn. Now that I am dropping a 454 into it, I doubt I will be doing much highway driving, so I will go back to solid hubs.
If you are just getting a clicking, I would guess that a U-Joint must be going bad. Have you tried to lift one side and see how much play you have before there is friction? Listen for a click noise?
There should also be some type of retainer keeping the shaft in (ie. axle bearing). If that is wearing out and the shaft is shifting, you will have some mis-alignment causing that sound.