12 valve.....does a ruber oring go on the lower groove in the injector? I never had them before, just themetal ring on the upper groove. But on the rebuild I have a package of injector parts, washers, return line brass peices, and 6 orings, that appear to fit perfectly on the lower groove of the injector.

 

the rubber orings are for after you install the injector and the injector nut. It goes between the injector and injector nut but do it BEFORE you put the injector lines on. Make sure you use the same thickness washer on the bottom end of the injector as what came off.