re supply ??

[Nokturnal]

To be honest i'm not entirely sure, never really used the trucks. But i would assume you have to use infantry and un-load the shells from the truck and then place them in the inventory of the mortar team.

[MrBouncabob]

While having the truck selected, press x and select the mortar. make sure you click the mortar itself and not the crew. Then move the Mortar rounds over. Close the transfer window and go to the mortar and open its inventory. Double click the shells and they should load.