Making A Cst 6" Kit An 8"

red87chevy · February 28, 2010

I just purchased a CST 6-8" kit very lightly used. The kit is in awesome shape, has the twin tower front a-arms with remote shocks and is complete. It has blocks for the rear (wish it had springs). Here is my question: My truck (2004 GMC 2500hd 8.1/allison regular cab longbed 4x4,3:73's) is currently sitting at stock height and i only want to do this once. CST's website says to make this kit an 8" you need to purchase the torsion keys and that you may need to modify your rear driveshaft. That is all they really say. Do i need to get the extended brake lines and has anyone gone the add-a-leaf route in the rear with the 6" blocks (as opposed to going with a 7" block) I would love to put 8" springs in the rear and be done with it, however i don't know if finances will allow it. Is the rear driveshaft modification definate on this lift and are there any other things that i should be planning on other than a regear to probably 4:56's?

Ideally, i would like to go the full 8" with this kit and put a 3" body lift to clear 38x15.50's. I know everyone says never go past 37's on these trucks, has anyone gone this route with the CST and had good success? The truck will not be wheeled to death by any means. Very light wheeling and not to frequently either? More normal driving and pulling trailer than anything else. Thanks in advance for the help!!!

700 sportsman · February 28, 2010

I can see the different keys in the front, and in the rear, I would normally say skip the add a leaf, but I think 7" blocks could cause axle wrap, which isn't good, so in your case, AAL might be the way to go, but you may notice a bit rougher ride, unless you can get 8" springs. I would say you would need a custon driveshaft going that high, but I'm not sure, and I think the brake lines may need to be extended also.