Hi Bill,
You are correct. My over-site. Early production listed the horsepower on the label. Later production listed the model (GX670). For parts, your best source is your local Honda Engine Dealer. You can use the dealer locator at engines.honda.com
These are not cheap aftermarket/rebuilt starters, so sometimes you can find used or 'factory' parts on Ebay or such for less.
Thank you,
Jim