We are a sub of a sub on a JBLM project but wasn't sure if we file a notice if the project is on a base?
Very typically, military bases are considered federal projects. That typically means the property is not subject to mechanics lien claims, and a claim against the payment bond (provided pursuant to Miller Act requirements, if present) would be more appropriate.
Preliminary notice can be mailed on the project. This is true regardless of project type - prelims are essentially just informational letters letting other project stakeholders know you're working on the job. And, sending such a notice to the prime contractor makes a lot of sense for sub-subcontractors - without that notice the GC may not know that the sub-sub is even working there. And, building familiarity early on in the job can help avoid payment delays and issues down the line. More on that here: Ultimate Guide to Preliminary Notice in Construction.
Of course, note that thorough project research should be done to ensure that the correct project type is identified, considering that different project types have separate requirements. Additionally, it looks like this may be a related question and answer which might be worth looking at: JBLM Project Q&A.