function onSelectEngine ( engine, type, vehicle_index )
 {
	eval('var make = document.vehicle.'+type+'make'+vehicle_index+';');
	eval('var emission = document.vehicle.'+type+'emission'+vehicle_index+';');
	eval('var model = document.vehicle.'+type+'model'+vehicle_index+';');

	emission.options.length = 0;
	
	eval('var length = ' + type + make.selectedIndex + '_'+ model.selectedIndex + '_' + engine.selectedIndex + '.length;');
//	eval('var length = ' + type + make.selectedIndex + '_'+ model.selectedIndex + '.length;');

	
	for (var i = 0; i < length; i++)
		{
		var temp = type + make.selectedIndex + '_' + model.selectedIndex + '_' + engine.selectedIndex + '[i]';
		eval('var opt' + i + ' = new Option('+ temp +' , ' + temp + ' , false, false);');	
		eval('emission.options[emission.options.length] = opt' + i + ';');
		}	
	}

function onSelectModel ( model, type, vehicle_index )
 {
	eval('var make = document.vehicle.'+type+'make'+vehicle_index+';');
	eval('var engine = document.vehicle.'+type+'engine'+vehicle_index+';');

	engine.options.length = 0;
	
	eval('var length = ' + type + make.selectedIndex + '_'+ model.selectedIndex + '.length;');
	
	for (var i = 0; i < length; i++)
		{
		var temp = type + make.selectedIndex + '_' + model.selectedIndex + '[i]';
		eval('var opt' + i + ' = new Option('+ temp +' , ' + temp + ' , false, false);');	
		eval('engine.options[engine.options.length] = opt' + i + ';');
		}
	
	onSelectEngine(engine, type, vehicle_index);
	}

function onSelectMake ( make, type, vehicle_index )
	{
	eval('var model = document.vehicle.'+type+'model'+vehicle_index+';');
	model.options.length = 0;
	
	var index = make.selectedIndex;
	eval('var length = ' + type + index + '.length;');
	
	for (var i = 0; i < length; i++)
		{
		eval('var opt' + i + ' = new Option(' + type + index + '[i], ' + type + index + '[i], false, false);');	
		eval('model.options[model.options.length] = opt' + i + ';');
		}	
	
	onSelectModel(model, type, vehicle_index);	
	}