I'm replacing the aftermarket water pump on an early (not carryover) 66 GT350 (6S379) with a correct C60E water pump. I have the AMK kit which has mostly conventional indented hex head style with lock washers. However, most all of the bolts I removed for the existing water pump are the castle style head. I have no idea if those are the original bolts that may have been reused previously or not. Just wanted to entertain that possibility with the experts. I think I've seen a period photo or two of 65 cast iron pump with castle style bolts. I realize this isn't Shelby specific, or that there may not be a definative answer. Just checking if any known trends. Were the castle style actually used for 65 cast iron pumps and carried into early 66 production, or random mix and match? Or, better to assume they're supposed to be the conventional indented style with lock washers and just go with that? Thanks for any inputs.