The infamous modular truck by exalt. Forgetting about the power source for 1 minute.

The modular system. If i have a customer that wants 2 trucks over 5000kg.
1. How many modules will i need to keep in stock?
2. How much will these modules cost.
3. If he then wants another truck 2 years down the line will i need upto date modules. If you have these clever people working with you surely they will be innovation and the trucks will be changing.
4. I have some modules i haven't used, will you buy them back?
5. At what price will you buy them back.
6. Is the option of a standard repair also available?
7. Where will you supply parts from? Europe or UAE?