[TexasLS1]

You likely have EEC being that your truck is a '72. To confirm, check the upper driver's side corner of the tank near the filler neck - there will be 2 fittings connected by a 3" piece of rubber hose. Also, there will be a steel line and rubber hoses behind the seat in the corner of the pass side (the steel line runs up the "B" pillar and loops back down to the tank). If you have all of these, your tank is EEC.

To throw you a curveball - if your tank is NOT original, it may still have EEC but need a different cap. I put a new Spectra tank in my '72, but ended up having to use a '71 fuel cap. I have no idea why they used a larger diameter filler neck on a new repro 1972 tank, but a new or old '72 cap would not fit it. Hope this helps!!