I have this, it seems to work. I am not 100% sure if the AI "knows" how to use it, I usually destroy these as soon as I can.
Transport Truck
I didn't make the art (I forget where I got it), I did make the button however, in addition to the XML code. Its all in modular format.
There are a couple things you have to edit to get it to work for you.
1. I.e. Remove the TECH_AUTOMOBILE as a prereq as well as the BONUS_RUBBER.
I have both In the game I use this for. I just didn't take them out. Just change it to TECH_COMBUSTION or whatever and it should work.
2. Additionally, the only unit this will carry (at the moment) is the Infantry. that is because i defined the Infantry with "SPECIALUNIT_SOLDIER" this was so the Truck wouldnt be able to carry the Tanks, Mech Infantry, etc...
I have it able to carry Infantry, Machine Guns, SAM Infantry, Anti-Tank Infantry, Marines/Seals, and Paratroopers. Grenadiers and Rifleman become obsolete before the truck is available so I didn't think it was necessary.
If there is a demand, I will upload it to the database with some screenshots. Otherwise Enjoy.