U-joint and pinion seal size question

[67redcudavert]

I have a 67 Barracuda with a 7 1/4 in it. I'm going to swap an 8 3/4 into it. I have two different center sections, a 741 3.23 open and a 742 3.23 posi. Right now the car has a 273 2V in it, someday it will get a 340. Looking at the 741 the yoke for the U-joint looks the same size as the one on the 7 1/4. Do they both use the same U-joint? I tried measuring them with calipers and they are virtually identical. The yoke on the 742 is definitely larger. I know that I have to shorten the drive shaft but if I could stay with the same U-joint for now it would simplify things. Also, since both of these units have been sitting around 20+ years I think it be a good idea to put a new pinion seal in. Is the size of the pinion seal different between the 741 and the 742? I've tried to answer these questions by looking at Rockauto but it wasn't real helpful on this.

Thanks, Gary

 

[Supershafts]

Only 2 joints and they are clearly different in size, so using the one that is the same size as the joint in the car will work.

If you want to be sure, you'll have to remove the shaft anyway, you can put it into whichever end yoke you're concerned with it fitting

 

[oldkimmer]

...............The 741 and 489 use the same seal..............742 is all on its own......u can get a conversion u joint to go from small u joint to large u joint or vice versa........kim........