First welcome to the site. Hope you find the information and support here helpful in your restoration (s)
On a 69 built at San Jose there was not typically a stamp applied to the firewall. San Jose had a different process than Dearborn and NJ ( they were also different from one another) and typically what you will find is paint inspector ink/paint stamps confirming that inspections were done. Many sub assemblies would also have assembler and inspection checks and marks but those would be shared with other plants and cars that shared the same supplier - not all plants received parts from the same supplier though
The unibody was typically stamped on the underside of the trunk lid while the following individual parts were stamped.
Fenders, hood, headlight buckets and cowl cover. There were at head two different versions of stamps the inspectors were using during 69 production some of the older guys ( in that position) continued to use an earlier version before changing over while another group us part of their name (first or last depending on how long it was) Patterns as to who was working and what style of stamp stamp was being used has been documented when available. For your cars period mostly the name were used for the stamps. I've identified 8 of them so far.
Some of these are shown in a basic paint mark article in the Library section of the site. Since your new you may not have explored that area of the site yet
Again welcome
