i am working on putting a sleeve hitch on my 1512 and took the tank out to build one out of steel that will be easier to fill and give me room for the hitch to slide right in the factory location. I noticed that the fuel tank has a tunnel in it for the rear pto so I came on here to see what it was all about. check out this old listing on epay of the fuel tank and you can see the tunnel molded in it for the pto.
http://www.ebay.com/itm/Cub-cadet-15...-/121198671340