I think I have asked this question previously and hae forgotten responses - so here goes again. I have a 316 ci in my 56 gmc. Near the firewall is a U shaped tube an inch in diameter and located in the valley cover by the distributor. 1.Is this the road draft tube? 2. can this pull oil out of the engine, I think this suposedly happened when the truck was new. We did lose oil out of the engine and trailed back and up the tailgate, like 3 qts low when we checked. Could this be the road draft tube that was the cause? thaks, tom