Combination U joint help!

[fr0bert]

Hi guys,  
Wondering if anyone can shed some light on this for me.  
This is my U joint from the rear driveshaft at the transfer case. The one from the rear axle is matching but pretty much disintegrated hence why I'm replacing them.


As you can see its a combination U joint which I've read here on other threads is a thing Ford seemed to do on these trucks. So I've been to two Napa stores this morning trying to find a replacement. The first store sold me this one... -


But as you can see, it has the C ring outside fitting on the 1" 1/16 end whereas I need the outside snap ring fitting on the end of the cap. It turns out... (after being condescended to and told that I was wrong and this MUST be the part "THE COMPUTER SAYS SO!" 🙄)... Napa don't stock the correct one... I need outside snap rings on the smaller cap.  

So after doing some digging and from googling "ford 1330 big cap" which i found someone call it that on a mustang forum I came across these two products which seem to have the same measurements but I don't know which one I need...  -  

https://www.dennysdriveshaft.com/p484_dana_spicer_5_7438x_universal_joint_1330_series_ford_with_2_.html 

https://www.dennysdriveshaft.com/p483_dana_spicer_5_1204x_universal_joint_1330_series_ford_with_2_.html

There seems to be some caveat about 'flat flange yoke' and I don't know what that means!  

Has anyone come across this on their trucks or can throw their 2 cents in?

Part of me wonders whether my U joints are original or not or whether I'm looking for a part that wasn't originally meant for my driveshaft...

Yours, terribly confused Rob in Virginia 🤦

[fr0bert]

Or am I completely over thinking this and the one the guy gave me would work just fine?!?

[ArdWrknTrk]

The U-joint comes with four internal (outside) snap rings.
I don't understand the issue?  

[fr0bert]

So I am COMPLETELY over thinking it 😂
I think my head got turned by getting an 'exact' replacement....

[ArdWrknTrk]

I think it's not uncommon for the aftermarket to consolidate part numbers and make one that is universal.

If you want OEM you can look the part up on Spicer's website.

[fr0bert]

Just did that, thanks for that.
Came across it on rock auto - https://www.rockauto.com/en/parts/dana,57438X,universal+joint,2392

Measurements seem to add up.