I know this not the right word and it may not apply to mustangs, but on the midsize cars where the shock towers meet the front and rear aprons there is a inside corner at the top that has a hole. There is some sort of pale,tan,off white color putty that is put in with a techs fingers. You can see that it is a very thick, not sticky stuff to fill the hole. My guess is a small wad and then pressed into the hole. Anybody got any ideas on what could be used today?