Dear Mr. Pfettscher,
Thank you for posting your request on History Hub!
We searched the National Archives Catalog and located a number of files related to Peacekeeper Rail Garrison. Most of these are Federal Railroad Administration (FRA) records relating to developing the related railroad technology and Environmental Protection Agency (EPA) files relating to conducting an environmental impact statement (EIS) for the program. The FRA files can be accessed digitally through our Catalog.
The draft EIS and the final EIS for the program are available through the Defense Technical Information Center, along with other documents related to the program. Other online official sources include the U.S. Government Accountability Office report Status of the Peacekeeper Rail Garrison Missile System NSIAD-89-64: Published: Jan 12, 1989. Publicly Released: Jan 12, 1989.
Unit histories and supporting documents of Air Force units are in the custody of the Air Force Historical Research Agency, 600 Chennault Circle, Building 1405, Maxwell Air Force Base, AL 36112-6424. To contact them please call (334) 953-2395 or send a message through the contact form on their website. Also, the National Museum of the US Air Force has in their collection a Peacekeeper Rail Garrison Car described by a fact sheet on their website. They may have additional information in their holdings. See this page about conducting research through the Museum.
We hope this information is helpful. Best of luck with your research!