I'll give it a search!
No, I'm changing the handling entries from the mods folder. The only entries I'm changing are Police2, Police3, FBI2, Sheriff2, PoliceOld1, PoliceOld2, and Police4, and even then I'm only changing the Handling ID to STANIER, GRESLEY, or BUFFALO2 and just replacing the dark tint with the clear.
*EDIT: I'm also only editing the vehicle.meta file, and not the handling.meta. Just changing the Handling ID for the vehicle (such as Police to STANIER)
*UPDATE: Downloaded this gameconfig (https://www.gta5-mods.com/misc/gta-5-gameconfig-300-cars) and all of the assets recomended and still getting the ERR_FIL_PAK_3 error