var baseImgUrl ="http://grfx.cstv.com/schoolslt/cars/graphics/";
		var imageRandNumber=Math.floor(Math.random()*4)+1;
		function randomMasthead(){
		document['rotMast'].src= baseImgUrl + 'cars-07-right-mast-random-0' +imageRandNumber+ '.jpg';
		document['rotMast2'].src= baseImgUrl + 'cars-07-left-mast-random-0' +imageRandNumber+ '.jpg';
		}
		randomMasthead();