I know the link between UV light and Vit B1 production, but I have no idea how UV light and cloacolith formation are linked? Can anyone help make the connection? Since UV light can't penetrate glass, anyway, I don't know what the vet is saying.

I'm sure that the "average" life expectancy has a lot to do with husbandry, and the individual snake's ability to acclimate. I can tell you this for certain, though, the vast majority of wild snakes die before seeing their first birthday. They produce a lot of offspring, but provide little, if any, parental care (it varies by species). I've read online sources that have claimed the "average" life expectancy to be about 10 years for well cared for snakes, but I doubt this was a particularily comprehensive survey. Another book I was just reviewing claimed the life expectancy for captive garters to be between 5 and 12 years. The rare captive garter snake has reportedly lived 18 years, or was it 20 years? It was one of the two. Again, your snake seems to have beat the odds and lived a long life. Despite the vet's comment, they just don't live forever. You were lucky, skilled, or both to have kept your snake for so long.
Rick

Can anyone please clarify the connection between UV light and cloacoliths? I can sure explain the connection between rough handling, stress, mineralocorticoid/glucocorticoid release, and death.