Blocks but unneeded stress on your U-bolts and leaf springs. You will get axle wrap under normal acceleration and will wear out your leaf springs...and fast.
You can see what blocks can do to your U-bolts. This is a picture when I lifted my 84' Toyota pickup which is VERY comparable to our trucks. The u-bolts needed to be cut out with a torch and DAMN was is scary when you cut all the way threw. Drew was there for that one. Haha. There is just no need to do blocks when you can get a single AAL for $65 or 3 pack AAL for $130.
And if your truck has ever seen salt it will be almost necessary for you to cut the camber bolts out to get the UCA out. I live in NY and my truck with 48k on it, I had to cut all 4 out. So get 4 new camber bolts, eccentric washers, and nuts from Nissan. So stock up on saws-all blades. I recommend Milwaukee Torch blades or DeWalt blades.