If I remember correctly it seems the old style had five air line ports that connect at the base of the controller. The newer style only has four. Here are some photos I snagged of the interweb. The fifth port has something to do with the charcoal canister which I also abandoned. These two valves are not interchangable but are mated to either the new style or old style airbox.Metal seated idle air control valve as opposed to? Picture? Definitive way to discern?