This is what happens when I apply an array modifier, and then a curve modifier to the two different types of segments to the tracks of this tank.
What am I doing wrong?
The curve is an edge that was converted to a curve.
Alright, here is the model if you think that you can fix it. https://1drv.ms/u/s!Ap6t_YOv62EQgg8AKBrwxLCwfzkg?e=nd4Nok
I don’t understand what you mean… If you want to fill in the space you can select the vert’s on either side and press f.
Additionally, I don’t know if that tread is deforming but usually the curve modifier will deform the mesh, so people use a plane that is arrayed and then the actual tread is instanced on those faces. This way the tread does not deform, the plane does. I would think that geometry nodes could do this too.
Hi, I just downloaded your file, it seems in that one you had filled the segment. In this case though you could try right clicking and selecting “Toggle Cyclic”. If that doesn’t work maybe delete a segment elsewhere to see if it at least works and then add it back with f.
Ok, checked out your file… had to set the origin to one of the vertices on the bottom of the curve, I got same result as you with any of them on the top. Then joined both parts together because I couldn’t get the dimensions to match without, maybe you could with some working out of dimensions, then I set the array to fit curve and played around with the relative offset.
I deleted most of the model so i could upload here, just append in. 
AbramsX2.blend (1.8 MB)
Thank you!