U joint bolts....what size

[orangebike]

81 chief with amc 20.....bolts that do ujoint to axle....they look like a torqs bit head with more teeth.....what is this called and what size is it...

[Tad]

U-Joint Strap Kit for a 1310 joint.

http://partimages.genpt.com/partimages/214532.jpg
http://www.napaonline.com/MasterPages/NOLMaster.aspx?PageId=470&LineCode=PUJ&PartNumber=43710&Description=Universal+Joint+(U-Joint)+Strap+Kit (http://www.napaonline.com/MasterPages/NOLMaster.aspx?PageId=470&LineCode=PUJ&PartNumber=43710&Description=Universal+Joint+%28U-Joint%29+Strap+Kit)

Pretty sure that's what you are looking for.
Carry a spare or two.
The straps stretch over time.

[Chevelleguy]

It's called a 12 point hex bolt.

[drduckman]

I can tell you from my experience that the ones on my 80 Cherokee had and still have some of the torx bolt heads. I got them off with a regular socket that was too small and I hammered it on, going to get new bolts and straps when I put it together. I went to the parts store and bought a set of External Torx sockets,less than $20. They fit the bolts like a glove.
Taking the original ones off was so far the first problem that I actually stopped working,washed my hands and then logged onto the computer to ask this group for advice about them,sure as heck wont be the last.

From what I have read, some auto mfgs used torx bolts and a few other oddballs to keep the average person from working on their own vehicles and to force more people into dealerships for service.