We've all seen the different Takagi cranks. But, what's the real difference? Timeline? Material?
My belief is bottom to top is older to newer. But, why doesn't the model in the middle say CrMo? Is it not Chromoly? I don't recall 180mm cranks in the late 70's, so, when did they come out? If it says MX is it different somehow than if it doesn't?
All are cast with T7 81 across the spindle area, and I know the bottom set was available in 1979, so, that's not date info. Any info folks have would be great.