I ran over to AutoZone and picked up the u-joints that are supposed to be for my truck. They are too small. But in checking to make sure I had the right joint (and realizing the ones I got were too small) I also noticed that my u-joints, at least for the joint where the axle attaches to the yoke on the diff is not the same size in both directions. In the picture below, the top to bottom dimension is not the same (is smaller) than the side to side dimension.



In this second picture I'm holding up the u-joint I bought for comparison. It is a little difficult to see.



Is the larger u-joint (the one with 1.126" caps and 2 5/8 yoke diameter) built "square" (like the new one I'm holding) or "oblong" (like the one that's on the axle)? Do I have some kind of conversion u-joint currently installed or is this just how it is supposed to be.

Thanks in advance for the edumacation.

If it is a 7260/7290, the Spicer number is 5-3140X.

3 u-joint size

7260=2 1/8

7290=2 5/8

1330=3 5/8 with a 1" or larger cap IIRC

I run a 7260/1330 conversion napa part # 240-0457

or its the other one that was mentioned already

Hey Scratchn, what is the NAPA # for a 7290/1330 conversion? Thanks, Lee.

7290/1330 conversion

I give my buddy at napa a call and get it though,would be handy info to have any ways

I know they found the 7260/1330 under a ferd/chrysler conversion IIRC

the 1330 has no clips on the cups.straps and tabs on the yoke only

ok checked my buddy at napa...napa has changed #s and now use a 3 didget #

7260/7290= napa#347

7260/1330=napa#457

7290/1330= napa#458

hope that helps

If you're working on the 68 or 69 in your pic, Dodge also used a Detroit 5380 in the 3/4 ton trucks and larger for sure, they're a little bigger than a 1410 and a pain to find. There's also a 1410 to 5380 conversion joint I've found while searching too if there's a chance that someone did some parts swapping at one point and you find two different caps.

Yeah, I'm working on my Swepty. It has an 8 3/4 rear in it though. It seems like it might be out of a different year truck or that the diff is at least different because it has the large yoke on the diff. I think I've got various u-joints sorted out but am off to the drive shaft shop today because we found this when we pressed off the u-joints.

Ended up not using either AutoZone u-joint I bought. I had to buy a 7260/7290 conversion joint from NAPA for the diff side. Then they used a 1310/7260 conversion (from Spicer) on the trans yoke side. The end they cut off and repaired was an odd diameter and they couldn't get it in 7260 anymore. Fun times. Now I have a drive line that no one will know what to do with in the future.

looks like a cap was spinning in the yoke from what I can see in the pic...

is that what was up with it?

maybe the time to get another shaft and build a good one with less conversion in it

so the slip yoke in the 727 is a 7260 and the end of shaft is the oddball yoke??

what # on the chunk??741,742.489??

seems I have to build a shaft every time I swap a tranz on rear axle

got a dozen spares in the shed various lengths and size yokes just for that kinda thing

welcome to old mopars

Best we can tell, a u-joint failed in the past. Rather than fix the shaft, the last person to put u-joints in just shoved one in. It was likely okay based on the surface area the cap could contact but why risk it?

So, the slip yoke is 7260. The shaft is now 1310 on the trans yoke end so I have a 7260 to 1310 u-joint. The other end is 7260 but the yoke on the 489 case diff is 7290 so I have a 7260 to 7290 u-joint there. The diameter of the drive shaft was 3.5 or 3.25.... can't remember. Either way, they could get one of those two diameter ends with the 7260 and I had the other.

Regardless, hot tanked, repaired, painted, new u-joints, and balanced for a buck fifty. Not bad in Atlanta I'd guess.