Peter, if you pull it down, under the fly wheel, bolted to the case is a plastic "seal ring". The crank seal presses into it and it goes over the crank. It also has a O ring on the underside. Look after it, its NLA. O rings no problem, its the same as the large one on the oiler. Make sure you use washers under the 3 socket cap screws and dont over tighten. Looks like the old aluminium tank, Im gussing they take the old style fuel line as well. You probably have the coarse thread crank which requires a specific clutch also.