Buying a second hand engine

Trying to buy a new engine as my one blew up due to a broken cam belt.

I've seen one on ebay, it's 2009 but has only done 44k, which is not lot for its ge. I phoned the guy and he said it's from a CAT B.

I asked if I could have the reg number so i could do a background check and he said he can't give out that information because it's a cat b. Does that sound correct?

I asked how he got the mileage and he said from an ecu check. Is that possible to do?

Appreciate any help