Hi guys. On the 103 cu.in. Dyna engines , as I understand it , when draining the transmission fluid , the fluid actually has to pass down through a hole cast in the engine oil pan in order to reach the drain hole. Obviously , where the oil pan is bolted to the gearbox casing , there is a gasket , but I've noticed that the gasket does not extend to seal around this hole where the transmission fluid passes out of the transmission casing 'through' the oil pan . My question is , what stops the engine oil / transmission fluid leaking into each other at this point ? There is a tab on the oil pan gasket to seal around the hole at the front of the pan ( which is blanked off by a plug screwed into the front of the pan) but not where the draining transmission fluid goes down the hole in the side !