1955-1985 GM L6/V6/V8 - 11 in. 26-Spline Sintered Metallic Disc with Diaphragm Pressure Plate;Includes 26-spline clutch disc for use with most 5-speed and 6-speed conversions; Designed for power levels up to 650 naturally aspirated horsepower (600 HP for forced induction/NOS); True “Street/Strip” clutch kit for spirited street driving and frequent track use; Upgraded damper springs gives up to 30% more clamping pressure than stock OE clutch; Dual friction disc offers the best of both worlds, smooth engagement and excellent holding capacity; Upgraded heavy-duty spring hub handles greater shock load over standard disc springs; All Street 650 clutch kits come complete with pressure plate, disc, throwout bearing, and alignment tool;