Radium Engineering lift pump extensions kit These lift pump mounts come standard with the 20-1990-XX, 20-1992-XX, 20-1993-00, and 20-1995-00 FCST-X. They were designed specifically for 39mm OD fuel pumps installed into 6 gallon, 10 gallon, and 10.5 gallon Radium Engineering fuel cells. The internal depth of these fuel cells is 7.7" (196mm). This is measured from the underside of the fill plate to the bottom of the lift pump filter sock. But these brackets are very forgiving with respect to fuel cell depth.