driveshaft problems.....please help

[owa1000]

So i picked up a 67 gmc swb and now im trying to get it on the road i have run into some problems. Im trying to hook the drive shaft up but cant seem to find the right u joint. The u joint that came on the drive shaft seems to be to small for the pinion yoke on the rear end. I dont know if this helps but I have a 400 trans and it seems to be a 8.5 10bolt. I have tried several u joints and either they are to big or to small. Does anyone know what i could do to get these things to line up. Im new at this and any help would be appreciated. thanks everyone

here is a quick pic

[mdwilf]

This is a pretty common problem. Take all the ujoints that came out of it with you to a parts store (you'll have to find one where they know more than what the computer tells them - probably one with a bunch of old guys working there) and tell them your problem. Some companies make "crossover" joints with different size cups on them or you may have to buy two joints to make one.

[eightbanger]

As stated above you may need a "crossover" UJ this is exactly what I needed but at the time couldn't understand why nothing would fit, this is when the UJ has to different lengths in one, this is needed when your DS UJ is smaller than your PY UJ.
Here's some pics I took at the time.

The UJ on the left was the wrong replacement I bought, and the one on the right is my old one the pic shows how the new UJ was the correct lenght one way but shorter in the opposite side.

[dznucks]

In what way is it too big or too small? and by how much is it off?

I ran into a similar problem awhile ago. I originally thought i needed a crossover ujoint too. If its not a u-joint issue then it may be a worn out yoke. The tangs on my yoke were .050" bigger than the overall length of the u joint. I didnt think the yoke could be worn out that bad. I was told this was caused from the ujoint/yoke bolts and strap coming loose, allowing the yoke to move around a bit. if you can, try and get the u-bolts instead of the two bolts and strap.

[Shyguy]

I had the same problem when we put a 3/4 ton drive shaft in a truck we built that had a rear end for a 1/2 ton.

I took measurements and the old joints to a place here, Fishers Auto Parts and talked to an old guy there. He took measurements and looked in his old catalog and came up with what he called a "Jump Joint' that worked great.

Fisher is also called Federated Auto Parts.

Danny

[brad_man_72]

measurements are great. And also what type of joint is good to know inside or outside keepers. Cup diameter and lenth\width. There isn't an accurate book on what vehiccle takes what ujoints, and after 40 years all bets are off anyways.

[eightbanger]

This is were I went for my UJ's and Pinion Yoke, they also have diagrams that you download print off and use to work out the exact size UJ for your application.

http://www.dennysdriveshaft.com/how_to_measure.html