I need a flue kit for a Modine 200,000btu furnace Model number PA200AB Serial number 15011050386 .. it has an oval shaped flue outlet size 7in height x 8 3/8 wide..no-one carries that size connecter .. I bought this used and I'm not sure if it had a draft insider mounted right there which would make sense or if it is supposrd to be natural draft..nowhere has been able to give me any information on this unit? Do you have any suggestions..?