Clanton made his debut in the then-NASCAR Busch Series in the 2003 Hardee's 250 at Richmond International Raceway.

In 2004, Clanton made his debut in the NASCAR Craftsman Truck Series, driving the #40 Chevrolet for Key Motorsports.

Sharing the ride with Stacy Compton, he ran in 16 of the 25 series events and earned five top 10s, including a career best of 6th at both Daytona and Atlanta.

During the offseason, it was announced that Clanton would take the sponsorship and number and run full-time for Roush Fenway Racing in 2008.

[2] After wrecking himself and teammate Colin Braun in offseason testing and then crashing out of the season-opening race at Daytona, he was released and replaced by Travis Kvapil effective immediately.