I considered making this a poll, but I'm curious the number that people throw out. I think she was 62.

There are so many lyrics ("hands of leather" "a dress she hadn't worn in quite a while") that suggest she is way older than 30-40. She also lived alone, suggesting that if she had kids they had moved out of the house. She was "Hell bent to make it on her own", meaning that she needed some help due to aging, but resisted it.

There is also some evidence that she isn't super old. For example, she still "had a need to feel the thunder" and apparently had a bit of energy left since the activities were "burning both ends of the night". He apparently also found her attractive.

Either way, I love the song. It has a great chorus, but is also so funny and gross that I can't help but jokingly belt it out every time I hear it.