Should I change my u joints?

The heep has 165000ish miles on it, and I don't imagine they have ever been changed. They don't show any signs of slop/play. Should I go ahead and change them. I have been doing all of the routine maint. type of stuff getting it ready to do some off roading, and don't want a u joint to bust the first time off the pavement. But, if they don't need it, I dont want to waste the time on them.

Also, if I do end up changing them, the Haynes book recommends replacing the straps with new ones...is this really necessary? How difficult is the whole job? It didn't look too bad in the Haynes.

96, 4.0, 231, 30" BFGs, 2" BB happening this week hopefully.

It can't hurt to change them, but I don't think you have to. It is not hard to change the joints. I usually use a 3/4 socket and a hammer, however you can get a press which is supposed to make it alot easier. I have never replaced the straps when changing joints, but having a couple of spares on the trail is not a bad idea.

Question? Which u-joints?

all the front and rear driveshaft u joints

I would check them and change them if they need it. But I've seen a few front driveshafts go for well over 200K without a problem, so I wouldn't bother unless they do. It's worthwhile to take the shafts off (at least at one end) and check for binding or stiffness even if there is no visible play, but if they're good I don't think you need to worry about sudden failures.

mine always vibrate under acceleration before they go bad. waited a little to long last time and it broke at about 45mph and crushed my muffler.

The vibes are making me wonder. I have no lift yet, and get vibes around 60 or so. Like I said, I can't find any evidence other than that that they are bad though.