I'm buying a Mount Vernon (not AE) from a coworker. He has a wall thimble which doesn't have provisions for an OAK to be passed through alongside the exhaust. I have a mobile home and from what I've read in the Mt. Vernon AE manual online is that it MUST have an OAK for mobile home installation. I'm planning on going by the code requirements when I install it ie. bolting to the floor and grounding to trailer frame just to cover my butt if I ever sell my home and the buyer has a picky inspector. Also for insurance reasons if the thing burns my house down. Is there a wall thimble available that allows both vent and OAK to pass through? If so, where can I get one? Are there any issues with the Mt. Vernon vs. the newer AE that I need to watch out for? I found out after I committed to the deal that it wasn't the AE model but I've seen it operate in person and it works well.