Any empty pole trailer loaded upon any truck-tractor (except pole trailers that straddle the truck-tractor bunks) must be fastened to the truck-tractor by not less than one 5/16" grade seven or better chain and one tensioning or locking device in such a manner as to prevent it from falling or shifting while in transit. The chain must be securely fastened between the forward point on the reach tunnel and a point on the truck-tractor frame or from either axle of the pole trailer to a point directly below the truck-tractor frame or crossmember.