C3AE-6015-?? There should be a letter or 2 at the end of the casting number. The HP cast in does designate a HIPO block. My guess either a 406 or a 427. Like Daffy427 said the 427 came stock with crossbolted caps. C3AE-6015-D or V is a 406 block and would not have come crossbolted from the factory. But solid lifter block, oil pressure relief and HD webbing and cranksaddle. The D block also has the crossbolt bosses cast in there where the V block does not. Those C2AE-6090-B heads are 406 heads. Does the crank have grooved journals?