The alternator regulator pack is a good one - and for the next 6 days we have the parts at 10% discount too:
https://www.dmgrs.co.uk/collections/...-and-yle102500
Inline thermostat is another favourite, but check yours is indeed running a bit cool before fitting:
https://www.dmgrs.co.uk/collections/...tat-89-degrees
The list macafee2 posted above is a good one - the usual checks often get forgotten in the day-to-day bustle, so now is a good time to take the time and check these over.