Richard....mine look to be an inch from the inside of the side lip twards the center and about a half inch from the inside of the lip that is on inside of the pump ..man thats sounds confusing to me...LOL. I wish I had Professor Bennetts photoshop diagram skills...LOL. If that sounds too confusing ...maybe fix the metal and "mock" assemble and magic marker where the holes are from where the top mounts to the side skins. That might be easier...LOL. Hope this helps and doesnt confuse you more my friend.
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Hubba: GAS GEEK , OIL FREAK and humble moderator