Looking at the different cranks by the conrod numbers they look the same measurements.
There are a lot of different Crank /Conrod markings ,I guess this must signify different years and batches of manufacturing the parts. The numbers would also be a way to identify rods/ cranks that are upgraded from older models.
The number on the lower crank case,I've heard some people say a 2 is for model 2 ,3 for model 3 ,4 for model 4 but I've seen 0 ,6 ,7 on models lower than model 5 , I think the 4 and other lower crank case stampings are to represent what parts go together when assembling the motors,as a possible example ,if the lower case had 4 it could mean the upper case after machining is 4 thou under the required optimal measurement for the crank to fit in with correct clearances so the lower case selected must be 4 thou larger to get the correct measurement to fit the crank in.
The lower case with a 0 would mean the cases are at the optimal measurements ,so 7 on the lower case would be 7 thou under measurement on the top case giving 7 thou extra on the lower case to bring the crank case back to the optimal measurement.
