if your talking KHC conversion, do you mean for Gen 2 shocks on a Gen 1 in the front, for the rear the shackle just sets ride height (more or less, it does change the arc that the rear leaf spring eye travels through as the suspension cycles), travel is limited by rear shock... unless your running an aftermarket shock, then you have to do your own math.... what i'm trying to say poorly, is the rear shackle does not care what shock is mounted in the back, you could even remove the shock, ride height unaffected... so the KHC conversion (I agree not crazy about hacking off shock/strut towers) really has nothing to do with KHC's offered three lengths of rear shackles (stock, +1, and +2).... hopefully that makes some sense or I misunderstood the statement...