I think I have this right, just need reassurance after searching the tech archives.

I have a 741 case yoke and It measures 2 1/8" inside to inside where the joint sits. ( picture is dark, looks like it's at 2 1/4" but it's not, it's at 2 1/8") is there where I should be measuring?

I also have a driveshaft from a 67 GTX, inside to inside measures 2 5/8" ( as shown in fuzzy crappy cell phone pic) did I measure this correctly?

I am thinking that the proper u-joint needed for my driveshaft will be a combination u-joint? The driveshaft has "grooves" for snap rings.

So a 7260 for the 741 yoke, and a 7290 (or 1310??) for the driveshaft? This is where I'm stuck. I'd like to have the info handy before going to the parts store. Thank you.

Here is the 67 GTX driveshaft with grooves for snap things in the ears...

I found this and saved it
Link http://www.driveshaftspecialist.com/HTML%20Measure/UJ%20ID%20Guide.html
Gus

Part numbers are listed for the combination u-joint suppliers at https://board.moparts.org/ubbthreads/showflat.php?Number=7177974

Looks like I need a 7260/7290 combo. I don't have an old joint to compare sizes of caps. I just have the information presented above. I'm thinking the 7260 side for the 741 case will use inside snaps and the 7290 will use outside snaps seeing I have grooves in the driveshaft ears.

I was just confused because all the tech archives and older posts point to a 67 GTX having 1300 series u-joints, not the 7290. Thanks for the info and charts and posts above

As said you need a "combo" ujoint of which several brands are available, for the rear. The "cross" will be 2&5/8 wide one way to fit the shaft and 2&1/8" wide the other way to fit the pinion yoke. After installing it move it back and forth & if it ain't smooth/with no binding then whack the ears with a drift/bfh till it's corrected. The "ears" are the 2 metal pieces on the shaft that connect the 2 holes in the driveshaft to the rest of the shaft. Set the shaft on the ground horizontle supported underneath it along its' length so the ujoint/yoke on the end is an inch or so off the ground then with one ear at 12 0'clock whack it then turn it 180 & whack the other ear then see if it is free & repeat as needed. Before you get to this point, when first installing it, driving the ujoint in with a hammer works better than compressing it with a vise surprisingly as a hammer is always my last choice on most situations. On the front trans yoke same deal, want it free in both planes of movement but sounds like you are good there & this is a pig change only in the rear

Yes, thanks only in the rear is the change. Actually reading the info and links above I'm supposed to measure the width of the. "Grooves" on the driveshaft ears, not the inside to inside as I did above on my picture. Because this has grooves, it's groove to groove which I measure 3 5/8" and that's a 1330 U-joint. And the 741 diff gets the 7260 conversion. I think I have this correct now.

I believe that all the Mopar Detroit type U joints, 7260 and the larger 7290, have internal retainers, the Mechanic type 1300 sereis u joints use external keepers some of the 1964 Plymouth had Mecahinc U joints stock and some had the smaller detroits, those are a real pain to figure out what part number is correct for which car That is one of those deals that you take the part with you to the parts house and start measureing very accuretly I still have one of those weird pionion yokes, it was easier to switch the yoke back then than to wait for that U joing to show up

on a 7260 U-Joint the outside of the caps on the U-Joint measure about 3 1/4 inches apx.
On the 7290 U-Joint the same measurement is 3 3/4 inches apx.
I recently worked on a 68 GTX with a factory Dana rear and it had 7260 I always thought Dana's had 7290's

All the Mopar factory Dana cars I've seen and worked on had the 1330 U joints I recently bought a Dana 60 out of a van to cut down and use in my 1966 Dodge 2 door sedan street car, it has the 7260 fine spline pinion yoke on it I'm probally going to change it to a 1330 or 1350, I have both yokes in stock