.09 Frame.

A. The chassis frame, for a body on chassis type vehicles, shall extend to the rear edge of the rear body cross member.

B. The body shall be attached to the chassis frame in such a manner as to minimize shifting of the body from the chassis under severe impact.

C. Alterations.

(1) Alterations in the length of the frame may be made only behind the rear hangers of the rear springs or forward of the front hangers of the front springs, or both, and may not be for the purpose of extending the wheelbase.

(2) Alterations may be made only if designed and guaranteed either by the original chassis manufacturer or by the company installing the school vehicle body.