Hi all, Most of the marks of the British and Canadian-produced Valentine tank were powered by the GMC 6-71 diesel engine (apparently referred to by us Canadians as the GMC 6004). The late model Valentines used a better version producing 165 BHP instead of 138. For the "Valentine 17 Pounder SP" aka "Archer", a variant of the engine was used which I've seen referred to as the "GMC 6-71M" which produced more horsepower - I think 192. Does anyone know where I could learn more about this variant of the engine? I presume, although maybe incorrectly, that the M didn't stand for "marine", as in the version of the engine used in landing craft. Although according to wikipedia that engine did produce more horsepower.