So I just bought a non-els pack and here's what I did. I got a free pack that came with a package install oiv file. I installed that and deleted everything from the vehicle.rpf and replaced the meta and carcol etc. Then I added in my purchased models. Some of those models spawn in and work fine (well the sirens don't work for some reasons but that's another thing). Anyways, some of the models crash my game when spawned in. What is confusing is that some of them actually work and others don't. All the meta files are installed correctly.
FIXED