Seals for Holley fuel transfer tube

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Just rebuilt a Holley and the new kit provided some sort of boots to seal each end of the fuel tube (connecting front and back bowls) - had never seem those before - normal sealing in past has been done with "O" rings. Not good so far - they both leak.

Is there some unique trick for installing these boots so they will seal properly (I did lightly lube the tube) and what might I have done wrong? Will go digging back into the left-over seals/gaskets to see if the kit also provided "O" rings as well, and probably will install those in an effort to end the leaking.

But, if you have experience with these boot type seals and can give insight on how to succeed, I would like to know. Thanks.