Should there be underbody heat shields on a 72 mine does not have them? I'm just getting mine on the road after hauling it home on a trailer 10 years ago, seems to be a lot of things missing or changed.
If you are referring to the heat shields under each seat, then yes, they are on the 72.
They were riveted to brackets which were riveted to the body. You should be able to see the rivet holes if the shields are missing.
Do you have the assembly instruction manual (AIM)? Any shielding installed on the assembly line will be shown in the AIM. If memory serves, various metal and plastic shielding is correct for your car, but I think the insulated underbody blankets were 68 and 69 only.