I don't have an exact match for a service manual but I've one for a '89 model year that covers about everything minus the diesel engine (got it from nicoclub ages ago but it got taken down since then - archive.org has a backup though) and a manual for the SD25 can be easily found on the internet, the one I have is meant for the SD25 in the Datsun 720 but who cares. My current setup is a 12V silicone heating mat wrapped around the fuel filter to prevent gelling problems, glowplugs are manual with a push button and I have installed a grid intake air heater from a yanmar diesel engine so it starts much better than in this old video.
I bought one about three years ago and at that point clutch sets were availible from a number of different shops here in Germany. I've no idea about other countries though.
