Finally getting to it!!! 1970 Duster 340

It's not a stencil. It was done with a rubber stamp. Cuda Cody on Moparts has a nice listing of stamps that you can purchase from the manufacturer using his fonts. It's great for the OCD restorer like me!

Mopar Stamps for Ink Part Numbers
Thanks for the link, I have watched Cody's how to videos. I will be ordering one for my 71 'Cuda since I'm OCD also.