Anyone know what the specs are, or the differences between the WME 92/93/53/68? I am looking at doing the 50hp conversion, and trying to figure out the differences between the carbs. They all use the same throttle plate, but is there a venturi size difference in the main throat of the carb. The 93 and 68 are both listed for the 50hp. What are the major differences, or are they interchangeable?