I alternate between the nav unit (updated to a Garmin) and the triple gauge (Jagwrangler upgrade) as the fancy takes in my 2001 XKR.
I note the 2 bulbs in the centre gauge have blown. OEM's are 14v 3w but these are not available in the UK as far as I can see - only 12v 3w. I can get Sylvania 2821 LL 13.5v 3w from eBay in US but not here. The shipping and import costs make this unattractive.
Question, does it really make a difference using the 12v bulbs in terms of longevity?

 

Any of the mentioned bulbs should be interchangeable with no practical impact.