15t – 10t CrawlMaster 550 Puller Pro V2 Rock Crawler Motor - Stubby or Standard TrailMaster Pro 540 Brushless Rock Crawler Motor. Axial Wraith 1.9. General Trail use: 27t – 21t TrailMaster Sport 550 (12t is not suitable for crawling) 27t – 21t TorqueMaster 550 15t – 10t CrawlMaster 550 Puller Pro V2 Rock Crawler Motor - Standard