Hello .. I am searching for an overdrive unit , I would really like the " Roverdrive" make as I have used one of these units. It is to fit on my RR classic 5 speed manual ... the standard high ratio box with the amazing power of the Mazda SL3500ti means I seem to drive everywhere in top and forth !! it would cope very well with the overdrive. cash waiting... also any comments about why I shouldn't use any other make , thanks Pete