First, THANKS for answering my previous questions:
I read somewhere recently (old Mercs.com ?) that gear lubricant for older Mercurys is Lubriplate 105, rather than a more modern gear oil. Can someone confirm this or is modern high viscosity gear oil A-O.K.
You're right, on these older outboards (1950's and earlier), stick with Lubriplate #105. Don't use modern lower unit oil, it doesn't give the proper protection. You can get Lubriplate #105 on-line, or they sell it at Napa auto stores.