Age of Darkness is a mod set in the historical period spanning the two world wars of the 20th century, revolving around the struggle between the forces of liberty, socialism and reaction.
Sadly, Indo-Iranian infantryman is sold separately (as is artillery and other equipment too).
So you first buy the truck, then can you buy improvements for it?
The truck is actually the prime mover for various factions. Generally, this is going to serve as a placeholder for almost all factions - until other prime movers can be introduced. Only Asian and fairly advanced nations get them. The Latin American, Eastern European and Muslim factions have to make do with horses.