Sup guys my name is brad an I own a 2007 classic sierra cc....an I wanna go witj a 4/6 but the more I read into it going that low has alot of issues that go along with that drop, I hear driveshaft issues are common....i also heat you need shims(dont know what those are or what they look like) what the difference in 16 & 17 inch spindle. Which is better? Sorry for being such a noob I have droppecother trucks they were jst all single cabs.....an from jst reading tney seem so easy.....any advice an info is appreciated. Im very OCD so everything has to be perfect an will not half ass a job so im reafy to learn l thanks guys for the help in advance!