Additional badge-engineered Morris 1800 and Wolseley 18/85 variants were launched in 1966 and 1967 respectively, catering for the BMC dealerships selling those marques.

[4] Subsequent modifications included changing, repositioning and re-angling the handbrake in October 1965,[4] removing the rear anti-roll bar and rearranging the rear suspension at the end of 1965, at the same time adjusting the steering to fix a problem of tyre scuffing,[4] and fitting stronger engine side covers in January 1966, along with modified engine-mounting rubbers which were "resistant to de-bonding".

The car's stance, strength and slow-but-sure nature over rough ground put the BMC rally crews in mind of a terrestrial crab.

Other changes included a higher second gear and final drive ratio for the manual transmission, and conventional suspension bushes replaced the far superior roller bearings fitted to the Mark I.

This had another change to the front grille (now a shared style for the Austin and Morris) and interior improvements, including a conventional floor-mounted handbrake.

In later life, the ADO17 became a popular car for competing in banger racing and in demolition derbies, owing to the bodyshell's strength, which made it ideal for those sports.

Australian-produced vehicles started out with a claimed local content of 65–70%, along with an undertaking from the manufacturers to raise the level to 95% in line with government requirements by the end of 1968.

[11] Initially the cars were generally identical to their British contemporaries; however, the local production was quickly modified to suit the harsher roads and climate of Australia.

Modifications to the British Mark I design included raised suspension trim height, the provision of a large, heavy sump guard, and better sealing against dust.

The Australian Mark II was notable in retaining the lower final drive ratio of the Mark I's manual transmission (but not the lower second gear), and, with the exception of the initial production run, was fitted with a dual-circuit hydraulic braking system manufactured locally by Paton's Brake Replacements (PBR) Pty.

Despite offering the safety of a dual-circuit system, it was generally held to be inferior in performance to the earlier Girling equipment.

In the Australian market, it offered a roomy and advanced 4-cylinder alternative to the popular 6-cylinder models such as the Holden Kingswood, which used conventional engineering based on American principles.

Some versions badged BMC Freeway (a name previously used for a six-cylinder Farina model in Australia) were exported to New Zealand, which also assembled UK-made Austin and Morris 1800s in separate plants.

As a one-off engineering prototype, to test production viability, an Australian 1800 Mark II body with subtly extended front guards and modified front internal structure was fitted with an early Rover 3.5 litre V8 mounted in the "North-South" position in the engine bay and then through a complex mechanical system, drove a heavily modified version of an "East-West"-mounted Borg Warner 3-speed automatic gearbox and Austin FWD differential.

[16] Both models had an updated dashboard and interior but retained the "bus"-like steering wheel position and gearshift approach from the 1800.

The X6 series was intended to compete more effectively with the Australian-assembled rear-wheel drive six-cylinder family cars of GM Holden, Ford and Chrysler Australia.

[18] Despite their technical superiority, updated styling, good ride, comfort, interior space and adequate power the "X6" series were somewhat underdeveloped due to a limited budget and so became ultimately commercially inferior to their competitors – eventually being superseded by the Leyland P76 in 1973.

Local distributor New Zealand Motor Corporation initially imported the Australian Tasman and Kimberley models from Zetland, but later assembled most of its stock from CKD kits at its Petone plant near Wellington.

In 1967 Pininfarina unveiled at the Turin Motor Show a concept car based on the Landcrab and designed by Paolo Martin, called the BMC 1800 Aerodinamica.