last week i bought a 99-00ish vortec 454 (gm test motor, has some not so 454 items on it, more like 496 stuff on it.) ive been looking for a flywheel but i can't figure out what fits. some web sites say all 454 flywheels are the same, some say up to 90, then 91 on are the same, some say up to 90, 91-95, and 96 on. GM sells a flywheel for this for around $100, but it says 11" pressure plate pattern. i want to put a 12" clutch on it. if my local dealer had one in stock, id just take a measurement to see if a 12" clutch will fit. but they don't and if i order it, im stuck with it. anyone know if it will fit or know of what flywheel that will fit the new 454 and a 12" clutch?