I have started working on my bronco again, I wanted to make the frame selectable so it can be changed in the future. I copied the main file from the pickup and renamed the old main file to bronco_frame, I also renamed the main slottype in bronco_frame to bronco_frame. the console says no nodes in main so it does not load, I am not sure what I did wrong.
You can't just change the main slot. As the name would suggest it is the main slot you have. To make the frame selectable you'd have to do it simmilarly to the D-series or the T-series. That is: have the main slot as a sort of slot hub with slots for additional modifications, paint jobs and the frame for example. From there you can go and branch out each individual slot such as the fram however you like.
If you chabge the slotType of a part which used to be in the "main" slot, you have to provide another part to take its place. You can't have your main slot empty as it will throw an error and fail to spawn a vehicle.