If originality isn't an issue, the emblems could be reproduced via 3D printing. The only emblems left on my own truck, aside from the "GMC" in the front grille (pictured in my avatar) are the "Custom" badges next to the doors. Somehow, those survived the abuse my truck has received from its previous owners.
Are these badges usually mounted with adhesive, or some kind of clip or pin? I haven't taken one off of a vehicle this old before.