Steering box rebuild 68 Dart 340

Car Nut said
Firm Feel is the top notch rebuilder of mopar steering boxes.

Firm Feel Inc. Steering and Suspension for Chrysler Plymouth & Dodge

I see that but do they use my original box or just a core they get from someone else? This is a numbers matching car that's all stock with original parts with a few exceptions like brakes and gas tank and I want to keep it that way.

Thanks for the replies.