Second Stage Manufacture vs State Vehicle Modification Approval

Commercial vehicle projects can fall under very different approval systems depending on when the vehicle is modified and whether it has already been supplied to the Australian market. A new chassis-cab converted into an ambulance, motorhome, fire appliance or other alternative vehicle before first supply can fall within the national Road Vehicle Standards framework and Second Stage Manufacture. A vehicle that has already entered service may instead require state or heavy-vehicle modification certification.

What is Second Stage Manufacture?

Second Stage Manufacture (SSM) applies when a new base vehicle is modified to become an alternative vehicle before it has been provided to the Australian market. The Australian Government states that the base vehicle must have an RVS approval, be entered on the Register of Approved Vehicles (RAV), remain a new vehicle and not yet have been supplied to the Australian market.

A second-stage manufacturer can apply for a Vehicle Type Approval that covers additions or modifications to the approved base vehicle. The completed second-stage vehicle is then entered on the RAV using the applicable SSM pathway.

When does state or heavy-vehicle modification approval apply?

Once a vehicle has already been supplied to the market or entered service, the approval question changes. For heavy vehicles, Vehicle Standards Bulletin 6 (VSB6) is the primary national code used for many heavy-vehicle modifications.

In Victoria, heavy-vehicle modifications that require certification are handled through the Vehicle Assessment Signatory Scheme (VASS), with the applicable engineering assessment completed by an authorised signatory for the relevant modification scope.

Why timing matters

The same physical change can sit in a different regulatory pathway depending on when it is performed. A body fitted to a new chassis before first supply can form part of an SSM approval strategy. Similar work carried out after the vehicle has entered service may instead be treated as an in-service modification requiring VASS, VSB6 or another state-based approval pathway.

Repeat-build programs

For body builders producing repeated configurations, a national type-approval strategy may be more scalable than treating each vehicle as a one-off modification. That decision depends on production status, base-vehicle approval, evidence coverage, configuration control and how the completed vehicle will be supplied.

How CVC can help

• Approval-pathway assessment before fabrication.
• VASS and heavy-vehicle modification engineering.
• RVS, ROVER and SSM consulting.
• ADR applicability and evidence review.
• Axle-load calculations.
• CAD drawings, calculations and structural assessment.
• FEA where technically appropriate.
• Model variation and configuration-compliance support.

Official guidance

• Australian Government – Second stage of manufacture
• Australian Government – Vehicle type approvals
• NHVR – Vehicle Standards Bulletin 6

Related CVC approval support

• Interstate Vehicle Approval Planning
• ROVER Compliance Support for Body Builders
• ADR Type Approval Consulting

Need to confirm the approval pathway before fabrication?

Send CVC the base vehicle, production stage, proposed modification and intended market so the likely approval pathway can be considered before fabrication is committed.

Technical content reviewed by Darren Ludecke, Managing Director | AVE | VASS Signatory. Updated September 2026.