Junk yard is the only place I know of and I know its no fun tracking it down or paying theyre rediculous prices anymore. you cant even pull your own dadgum part in some places.
you may be able to find some s10 enthusiasts out there with shops or parts too.
keep in mind other harnesses may work, you just have to research it. by ecm number on differnt vehicles, by accessories or part number at the dealer... there are a few ways your could do it. obviously the vehicles would all have a 2.8.
the most likely victim will be a cavelier or one of chevys cars - or something of like size.
good luck man I know its a paoin in the butt!