Mopar sells them together with an MSRP of (gulp) $1985. We can offer you one for 25% off that price if you want new. There are probably some used alternatives out there as well, but we are always careful when someone dismantles a Viper engine for parts. We got burned with a set of heads that were supposed to be "pristine" yet both arrived cracked - and no refund was ever given. Make sure you deal with reputable sellers if you go the used route.