Vintage Power Wagons told me the '66 flywheel I have is for the 4 fingered pressure plate and I can't use it with the common 12-inch clutches, unless I find a 4 fingered pressure plate to rebuild.

I don't yet know what kind of clutch is still on the '61 D100 with the 3 speed or whether its flywheel is drilled for the 3 finger P/P.

NOT saying VPW is wrong, but I would drop by http://www.sweptline.org/forums/ and see what they have to say. You may get a clear answer based upon someones direct experience.

VPW said that I can have my flywheel re-drilled for the 3-finger pressure plate. I could get a used 4-finger 11-inch p/p and have it rebuilt.