Looking for advice from anyone else who had nightmares of their stock drive shaft shooting through their Disco 2 transfer case, and purchased the Heavy Duty Driveshaft.

I actually bought mine from somebody who had the HD installed but the U-Joint went. I bought a new U-Joint but it didn't seem to fit, the caps were a tad too big. Interestingly enough, I pulled a stock driveshaft that I had on a parts rover and the U-Joint fit fine, so I put it on (It was my daily driver at the time, I get it). It be ridiculous not to use the HD driveshaft, so I'm trying to figure this out.

Is there a more specific U-Joint I need to order for the HD draft shaft? Anyone swapped one of these out and hit the same problem?