RS2000 came out in RHD form in late 1973. The twin cam (lotus rather than BDA powered) first appeared in 1968, the RS1600 (BDA powered) in 1970, the Mex came about at more or less the same time and used the crossflow. It's name came from Ford's success in the London to Mexico rally where the crossflow was used in preference to the BDA which was considered too temperamental for long distance rallying.
Geek, moi?