Modifications & Assessment

Chassis Line Toowoomba has had Approved Persons authorised by Queensland Transport since 1984. Our approval codes are listed below.

Mod plates or “blue plates”are something you should definitely look for on any used vehicle you are purchasing especially if you think the vehicle is no longer original. With a truck you can obtain a build sheet from the manufacturer that will provide you with the information required to establish if the vehicle is still original. The same applies to some trailer manufacturers.

There are still many vehicles out there that have been modified that have slipped through the system; generally these vehicles even though they have been in service for some time, have not been modified as to the Code of Practice & in some instances have been expensive to resolve.

Chassis Line in Toowoomba offers modifications as a service or we can certify a previous mod for you. Please check the below list, you will quickly appreciate just how many everyday fit-ups trigger the requirement to get a mod plate certification.

If the modification your require is not there follow the Queensland Transport link below to view all the codes, the department will advise you on who is your closest certifier. If this process is too difficult due to your location or circumstances please contact our engineering department, they can assist with the certification & work jointly with any certified examiner.

Modification plates are also applicable for some trailer repairs or refurbishments that are required from accidents & general wear & tear. Chassis Line Toowoomba hold all the required codes which are in the below list.

Chain of responsibility & duty of care places the onus on the owner of the vehicle with regards to modifications that are not certified & may expose you to monetary fines, insurance cover issues & down time if not addressed correctly.


LH4 Modified Wheelbase Conversion
LH7 Body/Chassis Variants Conversion
LK1 Seat & Seatbelt Installation/Removal


A1 Engine Substitution
A2 Air Cleaner Substitution or Additional Fitting
A4 Exhaust System Alteration
B1 Transmission Substitution or Additional Fitting
C1 Tailshaft Modification
D1 Rear Axle(s) Installation
D2 Differential Substitution
E1 Front Axle(s) Installation
F1 Suspension Substitution
F2 Trailer Suspension Modifications
G1 Air Brake System Relocation of Air Brake Components
G2 Installation of Trailer Braking Controls – Air Brakes
G3 Trailer Brake System Upgrading
G5 Fitting of Auxiliary Brake Engine, Exhaust or Retarder Type
G6 Air Operated Accessories
G7 System Substitution or Wheelbase Extension Powered Vehicles


H1 Wheelbase Extension Outside the First Manufacturer’s Option
H2 Reduction Less Than First Manufacturer’s Option
H3 Wheelbase Alterations Within First Manufacturer’s Option
H4 Chassis Frame Alteration
H5 Trailer Chassis Frame Modification
J1 Body Mounting
M1 Fuel System Alterations
P1 Tow Coupling Installation Vehicles over 4.5 Tonne GVM
P2 Fifth Wheel King Pin Installation
Q1 Installation of Truck Mounted Lifting Systems
R1 Goods Loading Device Installation
S1 Gross Vehicle Mass Rating & Gross Combination Mass Rating
S2 Gross Vehicle Mass Rating – Non Standard or Special Vehicles eg. Motorhomes
S3 Gross Combination Mass Rating for Non-Standard Vehicles
S7 Aggregate Trailer Mass Rating
S8 Road Train Prime Mover Rating
S9 B-Double Rating
S10 Concessional Livestock Loading Vehicle Rating
S11 Road Train Trailer Rating
S12 Aggregate Trailer Mass Rating for Non Standard Trailers
T1 Construction of Tow Trucks

NOTE: If the answer to any relevant question is “NO” on the above Modification Code Checklists, the modification is not acceptable