Rebirth - Repair

Hey all,

Was just thinking about this the other day and everyone i asked couldnt give a straight answer.

When is it considered not repairing and becoming an actual rebirth.

Because you can swap motors, bodyparts, pretty much everything. The only thing i havent herd of is switching Chasis.

Like what is the only part you cant change to make it a rebirth, cos if your car gets in a major accident you'll have to change a lot of things.

Sorry if i havent explained my concept enough
any body got ideas?

the firewall is the main part that holds all recognition
i'm not too shure but i dont think our allowed to change that?
i have seen rebirths before and they just cut out the vin numbers and weld them in
looks bodgy
they also Xray cars and can see that they have been welded up

ALot of Jap import before was rebirth, this is not allowed anymore