Why do you need native GDL? There are plenty of good military models in the Google Warehouse. If you have access to SketchUp Pro you can export as 3DS. If you need to rotate the tank turrets you can save them separately from the track/chassis. The 3DS import even gives you parts with detailed control over the materials (though it can be a trick figuring out which is which).
I have M1 Abrams and Jeep Wrangler converted years ago from 3DS meshes.
Best Rafał //Archicad since 4.1 version //MacBook Pro Retina 2019/2.4 GHz/Intel Core i9/32GB RAM/Radeon Pro 5500M 4GB/macOS 13.6 //Razer Intel i9/2.5GHz/32GB/Nvidia RTX 3080/Windows 11 Pro //ArchiCAD 28/Twinmotion 2024
Best Rafał //Archicad since 4.1 version //MacBook Pro Retina 2019/2.4 GHz/Intel Core i9/32GB RAM/Radeon Pro 5500M 4GB/macOS 13.6 //Razer Intel i9/2.5GHz/32GB/Nvidia RTX 3080/Windows 11 Pro //ArchiCAD 28/Twinmotion 2024