Power Thrust 2 Spring Brand: Scorpion Part Number: 021512 Notes: Higher engagement clutch spring for the Power Thrust 2 Primary Clutch on the 1977 - 1978 Scorpions, Neutral Spring for the 1979 - 1981 Scorpions. Should yield around a 3600 RPM engagement with the stock weight arms in 1979 - 1981 and around a 4200 RPM for the stock weight arms in 1977 - 1978 according to my books. Price: $15.00