See you asked Dynacorn a question but got a confused reply.
I re asked the question after googling what HDT and TG were.
No they're not Holden components.
I re-asked the question with information a bit clearer.
"Hi, My Panelbeater wants to know the Heat Deflection Tempreture, and the Glass Transition Tempreture of the resin used for the 67 Mustang Shelby hood 3641U but it isn't in the description. "
Whether they give you an answer is debatable as they might think of this as proprietary information to manufacturing the hood.
Although I would imagine if they had made enough of them they would have the process right so there was use of a stable enough resin to suit the application.