I've been internet searching for two hours now and cannot find an installation manual for my SD31. (I would settle for the SD50). I have found the schematic for the lower unit but not a manual. I have recently purchased a boat which has not been used for a couple of years and want to service the saildrive and replace the seals.
The post on this site dated 2007 reaches a link that no longer has the manuals.
On my SD-20 saildrives, they each came with a service manual. The installation manual was separate, and it was for the engine, with a section on Saildrive installation