your request does not tell us what we really need to know.
if you referring to a 1960s era MUSTANG Shelby replica, like my 1966 GT 350 clone, then go to a magazine store that sells car mags and get a copy of several of the mags that feature EARLY Mustangs as there are many parts suppliers that sell reproduction parts that advertise in these mags : Mustangs and Fast Fords, Mustang Monthly etc ....or get a Hemmings Motor News. Or check out this site :
http://www.vintage-mustang.com/
if you are talking about a Shelby roadster replica,then you have to be more definitive about what brand you have and specifically what you are looking for . Bill