So I can't decide if this is a dumb question or not. Is there a decent way to tell approximate age of a timing belt?

The engine on this bad boy has supposedly been "rebuilt" within the last 5k miles. I have no idea what the definition of rebuilt was in that instance as the guy I bought it from wasn't the one that rebuilt it. In theory, that means the belt shouldn't be more than 5k old.
I have the front torn down to where I could replace the timing belts, as I was planning to do it out of principle being a new owner and what not. The belt I ordered ended up being the wrong belt, so now that I need to get another one I'm starting to ponder if I'm just making more work for myself. The current one looks pretty solid. Any recommendations appreciated.
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