The R6 engine was developed from the BMC E6 engine used in the Princess (UK). Leyland Australia turned the engine into a 2.6. The tooling was then sold to Leyland ZA and the engine was used here in the Marina, Rover SD1 and Land Rover Series IIIS. The IIIS was our version of the Stage1 V8, but with some differences...gearbox and engine, mainly. Stellenbosch only worked on the cam and carburation for the Landy application, IIRC.