What Size U-bolts?

[rsfoster]

I will be looking at swapping out the stock 1.25" lift block with the Zone 2" version. The lift blocks come separate from Zone and there are several u-bolt diameter and length options. Anyone have an idea as to which u-bolts should be used on a 2010 Sierra?

 

Also I have noticed that certain companies offer both tapered and non-tapered version is there a particular style that should be used and are there any concerns one should have regarding dissimilar

I will most likely run the RC 2" level up front.