Oh, well I remember now.
I used 3dsmax 5 (Yes I found it somewhere on the internet...) with a XSI 3.0 exporter (the same as Duncan_10158 is using in his tutorial).
I made a new Hummer model, avoiding symetric things, and things which made me fail last time with this vehicle. The fish wasn't enought for me
So here is my new vehicle, with its own 6 x bullet rifle (new effects & sounds).
Thank you for having helped!