Yes ofp support 8-wheeled vehicles but you have it wheeled with a cannon on top if you want to make a wheeled vehicle to fire shells it is not possible well it is possible in 2 other ways
1-you make it act like a tank class but the wheels than won't turn(that will look ugly but trust me it is not possible with the current OFP engine till BIS update the game engine :-\)
2-you make it fire bullets explosive bullets with reload time's after each 1 shot 3 a 5 seconds than the wheels can turn without any problem(I suggest you to do it on the second way
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The model looks great m8 sorry I am not good at cpp files I can't help you with that try to ask some OFP guru's they can help you with it first when you say to them they say about firing shells it is impossible but tell them you want to make it shoot explosive bullets with reload times like I mentioned than all be allright goodluck with it m8
And here is your list