You have a non-EECS tank there. The two nipples are the tank vents for an open tank venting system, used on 49-state cars. EECS tanks have one nipple on each front corner of the tank.
To correctly install this tank, you need the small plastic surge tank that ties the two vent lines together at the top. I believe it is reproduced since all 68-70 carlines used it. Either Fusick or Supercar Specialties should have it; both are highly respected Oldsmobile vendors.
If you can't lay hands on one of them, all you need to do is run a piece of fuel hose from each nipple, to a point a few inches above the top of the gas tank. There's a retaining clamp on the passenger side underbody to run them thru. You will be able to see what I'm talking about once the car's in the air.
With the vent lines in place, use a non-vented gas cap.
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Glenn Williamson
Rocketraider
member AACA and all major Olds clubs
1964 Starfire, 1969 Toronado, 1974 Hurst/Olds, 1976 Ninety Eight
There's a Dodge K-Car and a Ford truck hiding in there too! Hey, ya gotta have something to beat around in...