Customs Official Uniforms

Costume Designer in desperate need of research help - I feel like I've telephoned half of DC trying to figure out how to access the CBP History Program's archives

I'm designing a short film featuring a border crossing scene at a port of entry in 1968, and need an accurate reference for the uniforms of customs officials. All I've been able to find are pictures of Border Patrol, who were a totally different department until 2003, and have been told that Customs uniforms have "always been dark blue."

I've enquired at the Border Patrol museum in El Paso, the Customs Museum Foundation in Florida, and have tried multiple avenues for contacting the CBP themselves, but all the menus are for people applying for Global Entry or asking about their immigration status - not people trying to learn about the organization itself.

At this point, I'm ready to accept information from someone who remembers going on vacation to Mexico in the 60s or 70s and could vaguely describe what Customs looked like.