will bad ujoints cause the truck to shudder in reverse if so how to replace them and how much will it cost

 

they could cause that.

the first thing to do to check them is to park the truck on flat ground, use the parking brake and/or blocks so it can't roll, leave it in neutral, then go under the truck and check for slack in the u-joints. if they have any slack you can feel in your hands, they're bad. also, if you see signs of rusty powder or anything like that coming out of them, they're bad. if they have grease fittings, grease them and see what comes out in the process. if they pass all these tests, that still doesn't prove they're good, but you'll know they aren't trashed anyway.

to replace them, you'll need some form of press. i use one of these https://encrypted-tbn1.gstatic.com/i...ZGgtoOcW58jReA but you can also use a hydraulic press if you have one. some people get by beating them in and out with a hammer, but that should be viewed as a last resort. some people try using a large bench vise for the job, but i broke a vise that way, so i don't advise it.
once you have a press, the job is pretty simple. use a pair of needle-nose vise grips to remove the clips from all 4 caps on the joint you're working on, remove the grease fitting if it has one, and then press one cap through as far as you can. usually it'll stop just a little before the opposite cap would fall free. use a large vise grip and a hammer to extract the cap. then press it the opposite way to push the opposite cap back out the way you just pushed it in. go as far as you easily can, then seperate the joint and drive the cap the rest of the way out with a hammer and a punch or whatever is handy (long screwdriver, chisel, etc). remove the joint from its other yoke the same way

once the joint is all apart, inspect the new joint and the yokes to see what position the grease fitting would be most accessible in, and make sure to install it in that position. remove 2 opposite caps, being careful not to knock the needle bearings loose, and start them both into the yoke from the outside. then insert the cross and slowly press the caps into it, again being careful not to knock the bearings loose. press the caps all the way in to their proper positions. at this point you'll probably be able to install the clip to only one side, install it and then gently press the joint toward it until the clip is under a little stress, then install the opposite clip. assemble the other half of the joint in the same way.
if at some point during the process you disturb the bearings in one cap, carefully stack them back into position, using grease to make them stick in place if necessary.

an experienced hand will take about an hour per joint, a newby could easily take 2 hours or more.

 

thanks how about cost?

 

Cost depends on brand... Generally greaseable joints are a few dollars more than the non-greaseable ones. If regularly greased theoretically they last longer.
Cheapo store brands probably $15 or under. Dana-Spicer joints are high quality and can cost more, but are worth it as they last longer.

Your problem could also be a clutch related, or possibly a loose rear pinion. Also check the slip joint if its a two piece driveshaft, I believe if they stick it can cause a shudder.