Possible to edit a vehicle from the game?

Is it possible to edit a vehicle from the game and still have it work? For an example if I took the pigeon and extended it. Would I have to remake the jbeam files sense the body has been extended along with other parts? So I did extend a vehicle as a test and saved it as Colada DAE to replace the original DAE. But it didn't change anything in the game. I have looked at the wiki but doesn't give much help when a vehicle that's already in the game.

Any help would be great thank you

 

Kinda a dumb question here but are you sure the change to the model was actually made?

And yes, you would have to modify the jbeam to fit the new model.

 

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Okay I saved the DAE. And I have to edit the jbeam file that's associated with the part that I modified. Parts i edited where the body frame and exhaust. I went into the body jbeam and things seem set up sections.

Since I've extended the body what would I have to do to edit the Jbeam so it's correct and corresponding with the extended body