The SLR 3-Pack gives 1.5" of lift...adding 1" SLR shackles gives a total rear lift of 2"....as their 1" shackles give 1/2" of lift, and their 2" shackles give 1" of lift, etc.

They label them by how many inches longer than stock they are...so a stock shackles ~ 3", and the 1" slr shackle is ~ 4", etc.

The rule of thumb is that for a centered axle, 1" of extra shackle length gives 1/2" of lift...as you are onlt raising the rear shackle point...the front end of the leaf pack stays put.



So choose how much lift you want and go from there....