Flashpoint (1984)

Two Texas border guards, a young hotshot and his older and more cynical partner, find a jeep buried for 20 years in the desert, with a skeleton, a scoped rifle, and a box with $800,000 in cash. They decide to keep the money, but quietly check up on the cryptic info they've found on the dead driver. Soon, the Feds are running all over the place, and it looks like the jeep may be linked to the JFK assassination. But the Feds are trying to cover it up, and eliminate anyone who knows about the jeep.