[Boris The Spider]

I do a lot of mission building and one thing I've noticed is that some of the vehicles available in the "Stationary Objects" menu are not available in the "Vehicles" menu. For instance, the Studebaker Truck. It's a part of pre-made convoys but not available as a single moving unit. There are other examples.

Is this something that can be modded?

(on a side note, is there a way to make custom convoys?)

Thanks, even if the answer is no.