Here is one of the most modern MBT in the world: The K2 Black Panther originally manufactured in South korea by Hyundai Rotem.

This mod brings the K2 Black Panther in polish colors to GTA V (Poland ordered the K2 for its own armed forces). It features a working main cannon and a seperate remote controlled MG.
The ERA blocks can be removed via tuning and it seats 3 people in total.

Before you use this, make sure to use the CWeaponInfoBlob Limit Adjuster by alexguirre to prevent the game from crashing during loading.