have a question how does one tell when the u-joints are going bad and how hard are they to replace? My Haynes manual is not extremely clear on the steps to take. My truck has 145,000 miles and I have a slight vibration, not sure if it tires out of balance or u-joint. Oh by the way it is 2wd and reg. cab.

 

jack up the truck and check for play in them, 145k it might be time. They are usually good for about 200k unless you drive on salty roads.

 

I think that you can get by with just putting the truck in neutral, get under the truck and see if the drive shaft has any play in it at the U-joints. Jacking up at least one side of the back of the truck would probably make this easier but it's not really necessary. You just want to make sure the drivleine isn't bound up in one direction or the other. There should not be any play in any of the u-joints.

 

I had to replace my u-joints this past summer on my 2003 3.0 L reg cab short box Ranger 115000 km's . What I first noticed was a slight rhythmic squeak when I was reversing into my parking space. I had gotten under the truck and tried to move the driveshaft to see if I could see any movement as well as having someone put the truck in/out of gear (automatic) to see if I could see anything and couldn't. It slowly started to vibrate and after a few weeks I decided to replace both because a u-joint is only $18 or so. It was my first time dropping a drive shaft on a rwd but have replaced many axles on fwd's.
It's not that big a job really. I did it in my apartment building parking lot in less than two hours. A garage with a bench vise is recommended or do as I did and get the 'loan a tool' from your local parts store. The big thing to remember is the drive shaft is balanced at the factory so everything has to go back together as it came apart. There should be yellow paint on the yokes or if rusted and dirty just spray some on yourself so you know how it goes back together.
By the way, there wasn't a needle left in the front u-joint. When I pulled the caps off nothing came out but rusty dust! Goes to show they can be really bad without giving much indication.

 

A bench vise is recommended. Do not take slip yolk apart and balance won't be an issue.
I don't recall you saying what the year is. There is models that use a nylon lock system. You can tell this style if there is a small hole in the yolk, not the cap, that you can see as a hole on yolk at each cap with white or blue plastic in it.
If that is the case than let us know and we will walk you through it as well.
I recommend spending the extra dollar or two and getting standard or inverted jerts and grease them every time ya change oil or get under truck for any reason. Proper maintenance and they may well out last your truck as the replacement is of better quality than OEM. I emphasize on getting replacements with grease jerts in them. Most parts stores you will have to ask for joints with jerts. As they tend to sell you non greasable ones as a rule.
I think because they will see you in a year or two and get to sell you another set. My Napa store dose and they have both on the shelf.

 

Sometimes before a joint loosens up, rust causes it to seize. The problem is you won't see any play because it's not allowing any movement. You can jack a wheel off the ground and turn the driveshaft by hand in neutral, often you can feel the bind this way. If in doubt, pull the shaft off at the rear and move the joints by hand, there should be little-no resistence, and the movement should be smooth, no grinding. I agree about getting a joint with zerks, and I'd recommend replacing both if neither has been replaced, who knows how long the other will last if one has already died, and stockers aren't greasable.