4 link tabs??

whats the easiest way to make sure all of them on a rear end are the exact same on each side

measure them

Do you mean the spacing from something, or how they are angled or what?

how there angled

calibrated eye!

Bolt them to the 4link bars, sit in place as close as you can to being identical.. measure each end from the framerails to a certain point on the tab/bolt/end. (at both ends of the bars) and that keeps them all identical pretty much. Can also check angle of the bars in relation to the framerails.. if they both match, and the distance between tabs/frame on both sides, at each end match.. the bars/tabs are identical (spacing/angles/distance from frame)

purchase an angle finder.

^ Yea that works if needing to find the angle they actually sit up and down, but if they're bolted to a bar end they should stay parallel anyway.. Just didn't know what he meant, like what measurement/angle he's trying to keep the same exactly.. =/

Digital Level

Chuck Norris' Eyeball.

But seriously.. let us know more about what exactly you are trying to measure. Hopefully you figure it out bro.