The beach cruisers I see often have big-style headlights, but they usually don't have dynamos--so I guess there's batteries inside the headlight. ...Some beach-cruiser bike companies sell accessories and various parts sparately, so you might check if you can just buy one that way.
The generator-style lights that rub the tire are also called "bottle lights", so you could try looking & asking around for that too. -If that was what you wanted (you could toss the dynamo and just run the headlight of some 6V batteries, if you have somewhere else you can stash them). Bottle light setups are just about commecially extinct in the USA, but they're still fairly common in Europe I understand.
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