Gilbert Prop Shaft U Joint fix

My truck has an upgraded prop shaft and I believe that is a gilbert. In the flurry to get my Ty back on the road I dropped one of the Caps on the U-joint and the needle bearings got scattered. The shop is a mess and I couldn't find all of them. I did some forum searching and the place to get a replacement is NAPA or O'Reileys, but here is my question. If I find te right u-joint can I take the cap and bearings and put it on the U-joint that is currently installed on the prop shaft? I am concerned that something could be off between new and old. I can verify with calipers, but did not know if that was a no-no in general. Also, is the u-joint pressed in? It has the equivelant of internal snap rings which I can get off but I don't have a press if it needs to be forced out.
 
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