total noob u-joint question

[uglyota]

how much slop is there supposed to be between the caps that are secured to the yoke on the pinion? None, right? Definitely not 1/8-1/4"? The nipples are there, but a 1310 seems far too narrow (1/8-1/4"), and a 1330 is way too wide to fit between them. This is a '76 3/4 ton truck 12bolt rearend and I'm trying to join it to a 1310 end of a driveshaft.
TIA

[sasquatch]

the yoke on the 9 i got from the yards on jefferson was bigger than my original yoke. there was about as much play in the newer yoke with the original u joint as you're talking about here, so i swaped yokes. didn't think there would be any difference between 76 and 78 but there was. i don't think there is supposed to be any slop between the caps and the yoke. to have as much 1/4" seems no bueno; if it moves around that much when spinning i would think it'd spit a cap. pop goes the u joint.

[uglyota]

that's what I figured, it's got mad vibrations

[stx4wheeler]

robert the 78 axle prolly came from a truck with a 400m motor in it so it had 1330 u joints thats why it didnt fit. no there shouldnt be any play eric, geta dial indicator and measure what both are supposed to be, and take those measurements to napa or the like and have them look in their book and find a conversion u joint for you.

[Sharpe]

I told you to go to napa and ask about the s44 joints numbnuts.

[RCcola55]

finding conversion ujoint sucks, right frick?

[uglyota]

now how I'm supposed to remember s44 when you knew I was riding my bike while I was talking to you? :D
jesse @ high angle said impacted yokes are pretty common on 12bolts. J&P will replace it for $25 labor. I feel more comfortable having it done by them than guesstimating preload myself on a vehicle that's about to go on a 1000 mile road trip