my 95 and old 87 blocks were the xxx,the yyy is a roller i just dont know if its an h.o. or notMustang78 said:i thought the YYY blocks were rollers..but you'd better check, every XXX block i've seen is flat tappet, my 302 H.O. has the XXX and my 68' 302 i'm building has XXX...
~Mark~