RevertRengar

I don't have any way i can articulate this better, but today i came across a pretty amazing server which has plenty of content which amuses me, mainly the cars and the maps. Is there any way to get this content for use in single player? I've tried going into the resources folder in MTA and replacing the respective files in GTA3.img, but the cars are invisible and upon seeing them it crashes my game, despite the DFF & TXD files corresponding to a normal car mod in size. What give?