Does anyone know what the height of the rear block on a Rancho 4" lift kit?

Also, is it possible to just buy the front part of the kit?

I currently have an AS 2.5" spacer and 3" rear blocks along with 5100's in the rear and would like to keep the rear intact and just redo the front with Rancho parts if possible. my goal is to get the geometry back.

Thanks,

Jeff