If Ex-wife is wanting a higher value, it's because she wants more money in some portion of divorce settlement...right?

Or maybe I'm reading too much into this also.

If you don't intend to sell, and parties need to know value in the interest of a divorce settlement, then the simple answer is to just pay to have the car appraised and let the unbiased appraisal answer all questions.

As for my opinion, I do think your $5k is far more realistic than her $10K. That's based exclusively on my interpretation of your verbal description, with no knowledge of pedigree/PHS info, no photos, body condition, history, etc...

And my opinion, as well as yours and your ex's opinions, are of zero value in divorce court.