I came across this add locally. I have a flywheel like it but with both the long and the diaphragm style bolt pattern. The flywheel is stepped in for the clutch disc. I suppose it requires a special pressure plate. Looks like it could use a 12 inch clutch plate. I am guessing its for a truck. It came with a bunch of 364 stuff I picked up. Any thoughts or info would be appreciated. The link is below. Buick nailhead flywheel - For Sale in Penticton - Castanet Classifieds
My guess is when Chevrolet used the Buick in buses and heavy trucks as the "torque master" engine. It had a 12" clutch as I recall.
This flywheel is supposed to fit 364 / 402 / or 425 depending on which one it is balanced for. The link explains that tid bit too. Buick Nailhead Flywheel 364, 401, 425 Motors Number FW10001 - PATC - TransmissionCenter.net A really old add for a 364 flywheel with the raised outer edge and recessed clutch surface for show and tell. Buick nailhead 364 401 Stick flywheel - Buick - Buy/Sell - Antique Automobile Club of America - Discussion Forums (aaca.org) This one from that old add has different chunks milled out for balance than your red one showing that they do balalance them for specific engines. Maybe one of our resident nailhead guys can fill us in on that. Easy to tell if you know what you are looking at, rather confusing if you don't.
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