If you search Youtube for a 70's TV show called BEARCATS you can find an episode, the first one, called the Devil Wears Armor. The show was set in New Mexico in the 1920's.
In this show the bad guy has stolen an Army Tank to rob banks. The tank is an FT-17 with a fake long gun. Some of you may know more and tell me I am wrong but it is pretty convincing.
There is plenty of footage of it on the move, people getting in and out. In one scene of the first bank robbery you can see a steady leak toward the back.