Lets assume that the vehicle consists of the following five components:
- Body
- Frame
- Drivetrain
- Suspension
- Axles
All of those five components must be original, but they may be reinforced or modified.
1. Body
- The body may be cut and shortened in front of the front axles or behind the rear axles, but not in between the axles.
- You are allowed to have an interior roll bar, but not external tube fenders or an external cage.
2. Frame
- The frame may be cut and shortened in front of the front axles or behind the rear axles, but not in between the axles.
- You are not allowed to replace the suspension brackets.
3. Drivetrain
- The drivetrain must be original, from the same model of the car.
- For example, a Wrangler YJ can use 4.2L, 2.5L, 4.0L petrol engines, but no Jeep TD engines. Toyota vehicles can use 4.2L engines only if that model had that as an option. A Wrangler TJ can use only 2.5L and 4.0L petrol engines, etc.
- The engine can be tuned, have turbochargers added and so on, but the engine has to be the one belonging to the exact vehicle model.
4. Suspension
- The suspension may be modified, but not replaced with another type of suspension.
- Lift kits are allowed, but for example on a Wrangler you are not allowed to replace the "short arm suspension" with a "long arm suspension" , original suspension brackets on the axles and the frame are also a must have.
- On a leaf spring suspension you may replace the leaf springs, but the brackets must remain on their own original position.
- No coilovers allowed except if a vehicle has it originally (OEM).
5. Axles
- The axles may be reinforced with other axle shafts, lockers, etc. They can even be tube reinforced, but the original OEM axle tube can't be replaced.
Additionally, tires up to 35" are allowed.