Well, welcome but first of all this is the wrong section. You should search better for the Modding Section below this forum. :/ Well you'll need 3ds max and Kams' scripts for it so you can export DFF and col. Well San Andreas modelling is different as you gotta know how to put textures, make TXD's and add car characteristics to the model like wheels etc. You can't just make a car model and get it ingame, it'll crash. I can't create cars on 3ds so I can't really explain in detail Also depends on the mod you want to do, there are models, textures, particles, etc. You can search some up in TGTAP's Mod Database and take examples from them (DO NOT COPY ANY CONTENT). Or you can go to GTAForums or google some modding tutorials