Oh man! This thread brings back the memories! Well, Menard's has the car. I told him it was a "custom undercoating" (LOL!!!). Well, actually, he had noticed while trying to secure the battery that there was a "greasy substance" on everything...YEAH FOOL! Rustproofing to last the ages! I'll go up there in 10 years and I bet the car will still be sitting there, completely rust free....with like 10 pounds of dirt stuck to it.
So the grease had kinda turned black and flattened out with time but it never really fallen off per se, just oozed a bit towards the back of the chassis. I did manage to light it on fire once when the catalytic converter overheated cause the carb had a fuel leak. That was fun. But I sprayed it with the garden hose till the fire went out and greased it back up again!
But reading this old thread...makes me wanna grab another mustang and start my old antics again.