Found a few issues when testing.
The first is the sight on the commanders GPMG for the Jackal seems to be missing/just a low poly block.
Also, and this is more of a me issue, the vehicles not air stuff disappears from being placeable when using some other mods. It's either 3CB BAF or CUP vehicles. Pretty sure its 3CB. Potentially class names conflicting. Your version of the Jackal looks better except for the commander GPMG.