Gunnery Sgt. David Tellefsen, enlisted career counselor, talks with a Marine aboard Marine Corps Base Quantico on March 25, 2014. The five Quantico counselors are the only Marines in their capacity to serve every active duty enlisted Marine, sergeant and above, Marine Corps-wide. - Gunnery Sgt. David Tellefsen, enlisted career counselor, talks with a Marine aboard Marine Corps Base Quantico on March 25, 2014. The five Quantico counselors are the only Marines in their capacity to serve every active duty enlisted Marine, sergeant and above, Marine Corps-wide.