bbc pro stock 500ci+,4.9"bore spacing,alum pro-filer hds,pn165-FB,12deg,54cc chambers,2"ex-2"x2 3/4"int,cnc ported,has valve guides,hd bolt inserts,valve seats,an fittings for oil&air,ex studes,one chamber needs repair,guides,seats.no valves,springs,retainers or rockers