Factory replacement Sealed-Power/Federal-Mogual VS-677 and VS-744 are both around 76-78 lbs on the seat and will take about .500" lift (same as comp 979's, 80 lbs closed). Comp 980 are 90 lbs on the seat. LT-1, Z/28 springs (VS-739R, comp 981) are about 100 lbs on the seat, same ~.500" max lift.