Theres a gazillion aftermarket/reman business' out there..& theres always OEM..
check Rock Auto for some names & P#'s..
My advice to you is, Change the bolts & GET QUALITY FASTENERS.. {ARP}
U didnt specify the year or mdl.. mechanical inj. or electronic..
Its not a fun job.. so have all the relevant info at your finger tips, change ALL crush gaskets & ALL orings.. & by all means, follow the torqueing sequences.. U only wanna do this job once.!!
Good luck.