Koni uses coilover sleeves mounted exactly the same way as GC's on their "full coilover" kits. The shock bodies themselves are not threaded. The spring perches are removable so the sleeves (regardless of if they're GC, Koni or whoever) can be installed in place of the perches instead of on top of them like with KYB AGX or Tokico Illuminas. So no, there's not really a difference between the Koni kit and buying GC's and Koni shocks separately.