ReadyLIFT customers have asked for it and we have delivered. Last fall we announced our new leveling and SST lift kit offerings for the all-new GM 1500 trucks. We specifically did not include the factory lift kit-equipped GMC AT4 and Chevy Silverado Trail Boss. The AT4/Trail Boss are factory equipped with a 2" front lift. This front lift includes a longer front shock/strut assembly. When combining a traditional leveling kit on these factory lifted trucks several issues present themselves including binding problems with the factory control arm ball joint and contact concerns with the lower strut/CV axle assembly.; The SST Lift Kit works with the factory 2" front lift. This kit includes a top mount strut spacer along with a pre-load spacer to limit droop and the same premium grade upper control arms now available in our leveling kit. OE style 3" tall cast iron rear lift blocks and rear bump stop extension cups are also included to create a true AT4/Trail Boss-specific bolt-on lift kit that provides 2" of front lift and 1" of rear lift. This new lift kit concept is similar to our successful TRD Pro Plus 2 SST Lift Kit which is also engineered specifically to work with that factory OE suspension lift. Your trust in ReadyLIFT to provide high-quality precision engineered products is extremely important to us. You can be assured that this all-new SST lift kits are the absolutely most reliable and best performing suspension upgrade option for the AT4/Trail Boss trucks.; AT4 - Max tire 305/55-20 20x9 0 offset wheel; Trail Boss - Max tire 295/65-20 20x9 0 offset wheel; NOTE: Use of Auto 4 HI feature not recommended.. NOTE: This GM 1500 kit is NOT COMPATIBLE with vehicles equipped with rear composite mono-leaf springs. The mono-leaf is easily identifiable the U-bolt is round/circular around the top of the leaf spring. This kit only works with vehicle equipped with traditional steel leaf springs identified by square U-bolts. NOTE: Not compatible with Sierra AT4X or Silverado ZR2 Edition.