I was actually going to do this over a private message but since the feature is broken and I couldn't find a way to directly contact Manus I want to do it from here.

Could I have permission to use and modify the model for the Land Rover Defender (With roof) in the DayZ Pack? I want to change it into an armoured riot
police vehicle with cannons that fire tear gas, would be an interesting concept.

Sure, use it

Could you send me the model file in a way that I can edit it in the toolbox? Thanks

You can already download it:

Most of my models are...

Oh wow, didn't realize, thanks!