Installing 3.5 inch Lifted Knuckle Suspension Kit by Rough Country | GM 1500 

Things I learned from DIY installing this RC 3.5 knuckle lift on my '18 GMC Sierra: * You most likely DO NOT need to cut into your cross member. I had a 1/32 gap between the diff and cross member on mine, which fit w/o touching. * You only need to cut back or grind about 1/4 inch off the two cooling fins on the lower diff next to the cross member. *video/instructions do not show, but it is much easier if you temp remove the swaybar inlay/link while installing struts and knuckle. * If you have a long socket extension bar, then you can easily get to the top 3 strut bolts on either side from engine compartment. This makes for easy torque settings at 37 ft-lbs. * Make sure bottom of the front struts are resting ABOVE the lower control arm mount when re-installing. * There is a typo in the middle of the instructions booklet says axle nut is 35mm. Incorrectl, it is 36mm. I torqued mine to factory specs 177 ft-lbs. * Be sure to pick up uncommon 16mm & 18mm wrenches before installing, since they are usually not included in most basic sets. * Reciprocating saw w/ metal blade is 10 X's easier & faster, then using a grinder to cut away diff fins and bump stock. Last - This 3.5" left is perfect height if you want to get away from the grandpa look or to run 33's.

If I do this knuckle lift can I use the rough country forged upper control arm?

Yea but how "lifted" is that knuckle compared to a factory knuckle? Is it even enough to help the cv stress???

Dont do it just replaced my cv axle because it make the angle jacked up and in 4x4 it will snap them