The A-10 tooling no longer exists. When the AF decided to re-wing the fleet, the tooling for the new wing had to be designed and built from the ground up.
Not true. There are a few acres of A-10 tooling sitting in the Arizona desert (AMARG). Perhaps not all of it, and not in the best of condition, either. But I’ve obtained many pieces and had them refurbished for production purposes. Boeing likely chose to fabricate new tooling because it’s easier (cheaper) than trying to refurbish/recalibrate old rusted out tooling. New tooling can be made using new, more precise technologies not available in the early 70s.