Re: 1970 Mercury 50 general maint. question
The seals on the Crowlley Marine site are for the driveshaft and are correct. If those seals need to be replaced one will face towards the LU gears and the other faces the waterpump housing. They keep the oil in the gearcase and not let it the aera of the waterpump and vise a versa. If there was no water in the LU and no oil in the pump housing the seals are probbly good and will not need to be replaced. otherwise the whole LU will have to come apart, to replace them, and would be better done by a ceritified marine machinic, as special tools will be needed to do the job correctly. I've never had to replace any of them in all the time that I've worked on those motors replacing water pumps. the seals are # 14 &15 on the Crowlley site. As noted on the other sites some kits will come with extra parts that is not needed inorder to repair just the waterpump. A call to Crowlley will get you just what you need to replace, repair the pump.
JMO
Oldman570