 Chassis made after the production run (service chassis) are slightly different, later ones have a triangular reinforcement behind the front outriggers, none of them have the front round tube going through the main chassis walls as it is more costly to tool and produce although it is stronger.The chassis wasn’t galvanised due to the additional cost it would add.There were also unfounded Health and Safety concerns about the gases involved in welding a galvanised chassis, due to the fact that supplying correct respiratory protection to welders would negate this problem.