I think the front drive shaft u-joints are starting to go on my '86. When the hubs are locked and I'm in 2H, I can feel and hear the movement in the front shaft over bumpy back roads. I checked underneath and there is definatly some slop in one direcion on the U-joints. I don't use 4x4 a whole lot, so its not an imediate problem if I just leave the hubs unlocked.
How difficult is it to replace u-joints? Are there any special tools required? I don't claim to be a mechanic, but I've been able to fix most of my trucks problems myself.... Is it worth a try or should I leave this to a pro?