Sound deadner/undercoating in the trunk?

Ford back in the day on every mustang I have worked on with out exception, they allways put the black undercoating on before the car was ever painted or primed. Wheel houses/trunk/front inner fenders/floors etc! On a nice original car you will see bleed thru of the undercoating thru the paint. So the rule for me is paint over the undercoating. Now if your undercoating it missing chunks and pieces it can be difficult to replicate what they did. After experimenting a number of ways over the years. the best way I have found and it does work, is use first a good urathane base bed liner, (Morton makes a good epoxy sprayable bedliner) test spray it until you get a nice look, experiment with the air pressure and distance away from panel being sprayed. Then spray the area that you want fixed. You can recoat after about 6 hours or so to build the area up. This take some time and patience! Then after it is dry take a product made by Wurth, this is a underbody seal that is excellent for having the right look. It says it is not to be painted over, this is because it bleeds thru the paint Giving the right look! One coat! If done right it looks great! I do it this way in all the area's ford did it back in the day. Now some might think this bedliner is wack. But to duplicate that thick tar ford did back then is very difficult! Of course epoxy prime first DP74 ect then put on the Bedliner/undercoating. I hope this gives some idea's. Now as far as your front fenders are concerned, they sprayed a coat after it was put together under the fenders and it was a bit inconsistant, but the idea was to get the underside of the top of the fenders so a rock would not fly up and dent the underside causing a nice inside out dent on the top of you fender. use the wurth product here by itself! Go to http://www.wurthusa.com/project/en/leftnavi/catalog/product.php?path=06.0510.jpg product number 0892 072 works great! it does take a good day to dry. Good luck on your project! Armond