If I remember correctly, the model has three or four different texture sheets. I think all of them have some pieces of the exterior painted on them, but the first texture deals mainly with outside. That being said, the model is broken down into three different parts - "A" which contains the trucks, cab, start door, and anything that ia animated, "B" which is any part of the model that is seen from both outside and the cab view, and Cab, which is the interior view. It looks like you have only been painting the "A" shape and first texture.
I painted the gp402.TgPcDx and thats about it. the other files are indecipherable. Help please.