I'm about 90% sure they do not offer any of the DLPT at MEPS. Even if they do, I'm not sure I'd use that time taking the test then, you have plenty of other stuff to focus on. However, I do know that they give you a whole briefing on it at OCS from a DLI (Defense Language Institute) representative. During this briefing they answer general questions about the DLI, when and where you can sign up to take the tests, and also drive home the fact that these tests are very difficult and that even native speakers usually do not score at the highest level. If I recall correctly they're 3 general categories of fluency. For lack of better words I'll just say they are fluent, very fluent, and expert. For obvious reasons, they are mainly interested in people that speak Arabic, Pashto, & Farsi. But they encourage anyone who has a language proficiency in anything other than English, to take the corresponding DLI test.