If you or anyone is interested... I have an Artic Cat 660T long block I purchased that I can not use. Bought the long block from a snow machine shop on Ebay. It was sold as a runner not a "core". My 1991 DD51-T uses the F6A so I have made other plans... going to use the complete drivetrain from a wrecked Suzuki X90. If anyone is interested in the long block let me know. I also have a complete gasket kit that I purchased and don't need. Thnx