REMINDER for others viewing the threads. These responses are tailored to the particular plant and production period. If you own another 68 Mustang or Cougar for that matter built at another plant or at San Jose but a different period of time these details may not original for your car!
Sorry no quick or easy way to do this - For the top picture in Reply #13
Light blue arrow - Typical sound deadener . Staying away from the ends/sides - top and bottom of the panel
Blue arrow - Appears they were having issues with the applicator, thickness of the product or air pressure producing a sub standard pass with the wand giving us this thin, ineffective effort.
Yellow arrow - No seam sealer was used on the upper or side edges of the bumper bracket to taillight panel. You should see a gap (large or thin between the two panels
Orange arrow - This seam would have had an ugly application of spray seam sealer producing a rough final look with sharp or feather edge depending on the angle of the application, thickness of product and or distance to the surface.
Green arrow - Same as above
Purple arrow - This area around the rear bumper bracket would have been non- brushed/wiped but instead pooled seam sealer applied out a spray type applicator
Red arrow - As a reminder the area around this hole and the one on the passenger side would not have any paint or primer on the untreated metal surface.
Related reference pictures
Will get to the last wheel well to trunk floor area to finish up todays requests