How do I tell what u-joint I have? My driveshaft is scrap, so I am ordering a new one from Mancini and have no idea what size u-joint is on the rear. It's an 8 3/4 with a fine-spline yoke and a 1 1/2 inch nut....

HELP!!!

It's in a 74 Duster with a 408 stroker sb, 727 and 83/4 on factory springs.

Carnage pics to come

Here's some info that I gathered

Spicer brand or "styles" of U-joint specs are:

1310, End of Cap to End of Cap 3.219", cap dia 1.063"
1330, End of Cap to End of Cap 3.625", cap dia 1.063"
1350, End of Cap to End of Cap 3.625", cap dia 1.188"

Mopar/Detroit joint specs are:

7260, Clip to Clip 2.125" or 3.125" EoC to EoC, Cap dia 1.078"
7290, Clip to clip 2.625" or 3.625 EoC to EoC, Cap dia 1.125"

SWEET! Ok, now to go buy a micrometer to figure out what I have. The rear seems to have a little play now, not really loose, but the yoke moves a little before the wheels start to turn. Keep in mind I was barely on it at around 2400 rpm when the trans shifted to 2nd and the u-joint failed. Should I tear down the 8 3/4? It's a 489 case from a 67 B-body.

I have been out of the gear head loop while deployed and am just seeing the car for the first time in almost 2 years less than a week ago, so any advice would be great!

Thanks again!

measure inside edge to inside edge of the pinion flange and 7260 is 2&1/8" and 7290 is 2&5/8". These 2 measurenents may be 3&1/8 & 3&5/8 but I'm sure on the fractions so w your tape you'll easily see what you have and the 1350 has ubolts instead of the straps like the other 2 common types have

lets narrow it down,,

you have a 408 stroker + SB 727.


I dont recall a SB 727 offered with the 7290 joint like some of the HP big blocks did..

a 13 anything is not possible unless the shaft was custom built..



a 489 wasnt stock for a 67 B body as they came out in 70/74 and could have either a 7260 or a 7290 yoke

so is possible that you had a 7260/7260 or a 7260/7290 or a 7290/7290..

Some small block drive shafts have the small joint in the front & the large one in the rear, if that helps at all.

Car was originally equipped with /6 and a 7 1/4 rear according to VIN. Knucklehead I bought it from swapped in v8 k frame and put a 318 with 727 in and used original driveshaft. Needless to say rear failed and he swapped in 8 1/4 rear. I got car , changed motors, blew trans and rear several times. Bought an SMR 727 then picked up an 8 3/4 that I was told came from a 67 b-body that is only an inch wider than a-body width, and spring perches are 1/2 inch wider. And i am guessing the u-joints are original size from 7 1/4....? I am unsure and everything about this car has been a nightmare. I learned the hardway about building Mopars and fast cars, so please don't beat me up to bad.

OK, so I lost my temper a little bit......

I called Mancini and had a driveshaft made with 1350 top and bottom u-joints and a new billet 1350 yoke for the rear. Hope this will stand up.


Anyone else use Mancini?

They said it should be on my doorstep by next wednesday....

a 489 diff is tempermintal when changing yokes... its not a unbolt, bolt on deal...