another thought if you are sure you want to use it. the spikes on the lower end are narrower than the top spikes and the left and right look narrow enough to put into the cutouts and once in the tube rotate 90 deg to a position parallel to the filler inlet.
I googled the name on the device and found nothing... was that a gadget available "As Seen On TV" back in the 70's when the change happened to unleaded?
GOOD LUCK!
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