I've had Craftsman 6 spd, GT5000 (917.276230) for 13 years - 25 HP Kohler Command Pro engine CV730-0029, has the 1.125 X 4.457 crankshaft. I did the head gasket upgrade some time ago, has 650 hrs on engine now, its been worked hard, deck and tractor are solid, engine needs at least rings at this...