Parken is correct. The spindle length changed in 1978. It got approx approx 2mm longer to accommodate CPSC mandated changes. This writeup on this BicycleClassics.com page is very helpful
Vintage Bicycle Parts : Bottom Brackets
You can use post 77 spindles with any year crank with minimal difficulty. You may have clearance problems if you use pre 77 spindles with later cranks.
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