B&M Nitrous HoleShot 3000 stall for 1965-91 TH400, 425 and 1968-81 TH350, 375 transmissions (Not TH350C) is an excellent choice for vehicles with engine modifications, particularly big cams that tend to reduce low end power and torque. The higher stall speed of this converter will launch the car in a higher rpm range where more torque is readily available, resulting in quicker acceleration. Nitrous Holeshot converters feature furnace brazed impeller and turbine, new precision steel alloy pump drive tube, new heavy duty needle bearings between the stator and impeller (not a thrust washer) and needle bearings between the stator and turbine. Other features include dual pattern 10.75 and 11.50-inch bolt circle, a new turbine hub, new springs and rollers in the stator and anti-balloon plates. The anti-balloon plates will allow these converters to stand up to the instant horsepower that a nitrous plate system delivers. Stall speed listings are based on engines producing 230lb. ft. of torque at 2,500 rpm. More torque at 2,500 rpm will give you more stall speed, less torque at 2,500 rpm will give you less stall speed than the stall speed ratings indicated. These are serious converters for serious performance street cars. To prevent contamination left from worn parts being circulated in your new components causing premature wear, we strongly recommend protecting your investment by adding a B&M transmission cooler with all new transmission installations. Listed converters are NOT to be used in trans-brake applications. Not for use in trans-brake applications. Has both 10.75 and 11.50-inch bolt circles. Fits GM 1965 to 1991 TH400, TH425 and TH350. Also fits GM 1968 to 1981 TH350 and TH375B. Does not fit TH350C models with locking torque converter