Hi I’m new to the forum and apologize in advance if I’m in the wrong place lol. I have an sl -7 heatnglo I need to go from vertical to rear vent. I need to block the sl top portion of the stove. It’s 4 inside and 6-5/8 outer. Any help would be appreciated as I can not find the block off that came w the unit thanks . Pic is of the parts that come of the horizontal part in the back I need the top .