Rear end, driveshaft questions...

I have just bought new axles for my 8 3/4 swap. I have been doing a lot of reading and I'd like to make sure I have things right.
From my understanding swapping a 8 1/4 for a 8 3/4 with a 904 tranny I will need to shorten the driveshaft 2 1/4". Does that sound correct?
Also I have read that It is a good time to upgrade the yoke. What yoke do I upgrade too? ?? Would I need new u joints then as well? Which ones would I get? Do I have to upgrade the yoke? What purpose does that serve? Also I seem to be missing the bolts, and the covers that hold in place the U joints on the case. Does anyone know where I could find them?
I think I have covered everything? I hope! Thanks for all your help guys!

BTW, I have a 360 with around 400hp, 904 transmission, and a 489, 3.23 sure grip that I am trying to install... correctly :)

Thanks.