The Tork Master 3000 fits 1965-91 GM TH400, 425, 375 and 1968-81 GM TH350, 375B (not 350C) transmissions. Don't let the exceptional value fool you into thinking Tork Master Converters are not packed with lots of quality features, making them the best value-priced street performance converters money can buy. These converters perform best when paired with stock to modified engines up to 350hp/350 ft lbs of torque, and lighter weight applications, like street rods. The Tork Master will provide noticeably quicker launches and harder acceleration while maintaining normal daily driving qualities. Upgrades like a new precision alloy steel pump drive tube, needle thrust bearing when factory equipped, new thrust washer between turbine and cover when required, and pressure tested and fully balanced by expertly trained technicians. Notes: Higher stall converters can generate more heat, so we highly recommend adding a transmission cooler. Not recommended for big block, supercharged, plate-type nitrous oxide or trans-brake applications. The product images shown are for illustration purposes only and may not be an exact representation of the product. 10.75 in. bolt circle