You can't really bend an SYE kit. Something will snap before it bends.
Adjustable uppers allow you to change your pinion angle.
Your pinion angle is likely not correct if you have stock upper control arms and an SYE on the t-case.
Having a u-joint fail can be an indication your pinion angle is off. Or maybe it was just a bad u-joint.
To determine if the axle pinion angle is correct, you need to take an angle measurement of the driveshaft and then take an angle measurement for the pinion. These angles should match when you have an SYE kit and double cardon driveshaft.
It can be difficult to get an accurate reading for the axle pinion angle. Another way to do it is to pick something that is a perfect 90 degrees from the pinion angle. The diff cover will be perfectly perpindicular to the pinion angle. You can measure the angle of the diff cover and subtract that number from 90 degrees. That will give you the pinion angle.
You can also get a good idea of the pinion angle by measuring, but an angle finder works a little better.
The way to measure the pinion angle with a tape is you have to rotate the rear driveshaft until 2 of the u-joint caps are perfectly vertical. The measure the distance between the u-joint cap and the pinion yoke on the axle. Do this for both the top and bottom u-joint cap and see how they compare.
Long story short, you want the single u-joint at the axle to basically have no angle on it.
