A guide to Body Sealers and Deadners

1968 New Jersey built Mustangs and Shelbys




July 4, 2020



The information on ths page is specific to 1968 NJ built Mustangs and Shelbys. If you are planning to restore a 1968 New Jersey built car, I would recommend you document these sealers before you start your restoration. Each car is different and as you will see, no two cars were identical. I am using information from original, unrestored cars whenever possible.



Trunk Area

The trunk area is probably were these sealers and deadners are most visible. The back side of the quarter panels had "deadner" applied. This heavy coat was to minimize rattles and quiet the car.


Depending on when the car was built and who sprayed the deadner, it may have been "side to side" or "circular" in an area approximately 18 inches.


I would describe this deadner as heavy and very textured in most cases.


This photo shows a typical circular pattern.


This photo shows a typical side to side pattern. The pattern was determined by the person spraying the deadner.


The deadner was applied before body color paint was applied and before any parts were assembled to the chassis. At one time, this was all white. You can see evidence that after the white was sprayed the car was rotated (most likely moved up a steep conveyor) to the next area of the assembly line. Extra credit will be granted if you duplicate those horizontal paint drips!


Here are some sealers in the trunk area. These sealers were often times a different product and applied differently from the deadner shown above. They were also done before body color paint was applied to the chassis.


This area where the wheel house meets the trunk floor was very heavy. The goal was to seal all gaps in the sheetmetal and keep the trunk dry.


The yellow stains on this trunk floor are actually glue for the trunk mat.


This car appears to have a more brushed look to the wheel house sealer. Neatness was not graded.


On a convertible, the sealer extended upward along the bracing.


The GT500 KR, 4 speeds (only) had sealer across the front of the fuel tank.





The area where the lower valence meets the crossmember also was sealed, it extends across the back of the car and outward around the small braces on both sides. I want to emphasize these sealers were done before any parts were added and before the car was painted.



Under Body Sealing


1968 Shelbys did not receive factory under coating, but were sealed in a few places after the car was painted.




The bottom edge of the trunk drop, facing the leaf spring has a black, brushed sealer on both sides.




The forward edge of the rear torque box is also brushed sealed. It extends upward to the front of the rear frame rail extension.




Each of the four seat belt anchors gets a brush of sealer around the edges.




There are four oval floor drain covers visible from under the car. These were installed after the car was painted and sealed with rope caulk. The original finish is galvanized steel. They may also have a spray sealer on the inside of the car (under the carpet).




The rear wheels have a sprayed deadner. This deadner does not cover the entire wheel wheel, but is used to seal the seam of the two wheel well halves. When the sealer was applied has been debated for a long time. Some people say before the paint, others say after.




The side cowl, behind the front fenders, was sealed with a spray sealer.




Normally, a Mustang would have a lot of sealer in the front wheel well areas. The bottom of the fenders did not get any deadner or gravel guard. On 1968 Shelbys, much of the sprayed sealer was deleted. This was most likely because AO Smith had to work in this area to assembled the Shelby front fiberglass.




This front headlight area had to be reassembled to add the fiberglass nose. The sealer was deleted here.