Hello eaglerock.
As the owner of the 1940 Derham bodied "one-off" that O_D mentioned, I am always interested in Derham built cars.
Over the years, I have seen several Derham bodied cars,all with the Derham shield on both sides of the car, just below and slightly posterior to the hood. In my case they are adjacent to and somewhat behind the sidemounts. I have never seen a single shield mounted on the firewall.
Derham was known to remove the Packard plate from the firewall and replace it with a simple metal plate having a set of numbers that were not Packard's, but probably meant something in Derham's production scheme. Packard would ship the chassis, engine and running gear to the coachmaker, The rest of the car would be built by the coachmaker to the buyers specifications. In the 50s, Derham did conversions of factory cars for Packard and others, but these were essentally modified production cars.
The suggestion that you contact others with similar cars and compare them is an excellent idea.
IMHO, I believe a prior owner attached the shield to the firewall hopeing in would enhance the value of the car.
Regardless, it is a fine car and I hope you have tons of pleasure with it.

Have been reading the posts on this subject with an open mind. First, let me say I am on this site daily, but do not post much as I do not feel as knowledgable as many others.

This is supposed to be an organ for interchange of Packard lovers. Most of the time it is just that.

I noticed some time ago, that Packard 53 was critical of certain PAC members. The two in particular that he took aim on are dedicated,knowledgable,kind people who I know for a fact, have helped out many,many Packard people. O-D/Dave C.. and Stuart B.

I do not know what Packard 53's problem is (maybe getting old and crochity) but this site is to help one another in Packardland. NOT for personal vendettes.

To O_D....you are and have been doing a fantastic job both on the PAC forums and on Packard Info forums.

Do not let one disgrunteld person stop you from continuing your most appreciated comments. Most of us look forward to your posts.

In the south Jersey,Philadelphia area, many Packard dealers became Mercedes-Benz dealers.
QUALITY TO QUALITY