The lift came with shims, at least if I go this route I don't need to go buy steel. Another damn it in this whole thing is that there are 2 foot x 2 foot areas of deep concrete where the lift posts go, problem is neither myself or the builder documented it! I know that I went further than the 3 foot minimum on the side for door opening ability, just not sure if it was 3 1/2 or 4 feet. There is no rebar or it would be easy to detect. Seems like some kind of seismic instrument could find them, something like they use to figure out how much dirt to remove for building foundation, dunno.