Monaro said

No, I'm talking about both rollers on the universal joint installed on the shaft not fitting completly into the seat of the diff yoke, so that I can't installe both the straps.

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TrailBeast said

I have to agree that it sounds just like a needle laying under the cap sideways.
Either that or the center cross of the joint is just a tad wide, and just because the caps are the same size does not mean it it can't be a wider joint.

Carefully pull those two caps straight off nice and easy.
Look to be sure none of the needle bearings are laying down flat in the cap.
Carefully and slowly ease the caps back on nice and straight.
Afterwards if it still does not fit it's the wrong ujoint.

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