I just got the 8 1/4 rear end and I was just wondering if I need to get new U bolts and a different drive line or since I have the sye kit do I need a different drive line?

The axle housings are bigger in diameter so you need the u-bolts and I think plates from the 8.25.

get the plates and u bolt if poss at least the plates and e brake cables still connected is a plus,u bolts can be gotten from auto jone in there suspension block kit 2 inch kit is cheapest ,get flat washers and lock washer added saftey throw the blocks in trash . As for ds it depends on how far your slip yoke out now ,8.25s about 2 inchs longer toward the tranny . What i did was just got a shorter shaft from a grand cherokee . Also axle tube being bigger get a little lift with the swap also...

I loved the throw blocks in trash part of the advice in your post.