By the 1970s, Opel had emerged as the stronger of GM's two European brands; Vauxhall was the third-best selling brand in Great Britain after the British Motor Corporation (later British Leyland) but made only a modest impact elsewhere. The two companies were direct competitors outside of each other's respective home markets, but mirroring Ford's decision to merge its British and German subsidiaries in the late 1960s, GM followed the same precedent. Opel and Vauxhall had loosely collaborated before, but serious efforts to merge the two companies' operations and product families into one did not start until the 1970s - which had Vauxhall's complete product line replaced by vehicles built on Opel-based platforms - the only exception to the rule being the Bedford CF panel van, the only solely Vauxhall design which was marketed as an Opel on the Continent. By the turn of the 1980s, the two brands were in effect, one and the same.
It had some crazy mechanical issues. At one point it stumbled and stalled because the carburetor had come loose from the intake manifold and I had to tighten it back down! Another time, my brother was driving it and the brakes failed. Somehow the end of the brake shoe that meets the brake cylinder piston had become worn on one side, causing the piston to slip off the end of the shoe when the brakes were applied, losing braking and squirting fluid all over.