I don't think it's a 'draft tube'. It has an actual slip-on breather cap on top, not a twist-on filler cap. Here is a picture at this link:
http://s838.photobucket.com/albums/zz304/jfgekg/Truck/ The filler in question is at the right, as seen from the passenger side of the truck. The silver thing on top of the filler is the breather cap. The vent pipe protrudes out just below the cap, then turns downward for about 6 inches, where it ends, open ended.
I don't know precisely what a draft tube is, but the pipe I have wouldn't be tall enough to come through the floor of a COE.
BTW I have the engine back together now and should be ready to fire it up this weekend or so!
