The catalog says 1/2A6-2, A8-3, B6-4, and C6-5. I would go with an A8-5 over the 3 as the modern A8-3 delays are very short, too short for the Drifter.

Take a look at your favorite old catalog for motor recommendations of other kits at this site, Ninfinger Productions: Model Rockets

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I love sanding.