function load_makes() {
    for ( i = 0; i < winch_plate_data.length; i++ ) {
        $('make_drop_down').options[i+1] = new Option ( winch_plate_data[i].make );
    }
}

function make_select_change() {
    // Clear existing models
    for (j=$('model_drop_down').options.length; j > 0; j--) {
        $('model_drop_down').remove(j); 
    }

    // Populate Models for selected Make
    for ( i = 0; i < winch_plate_data[$('make_drop_down').options.selectedIndex - 1].models.length; i++ ) {
        $('model_drop_down').options[i + 1] = new Option ( winch_plate_data[$('make_drop_down').options.selectedIndex - 1].models[i].name );
    }

    $('model_drop_down').disabled = false;
    $('query_button').disabled = true;
}

function model_select_change() {
    if ($('model_drop_down').options.selectedIndex == 0) {
        $('query_button').disabled = true;
    } else {
        $('query_button').disabled = false;
    }
}

function goto_product() {
    var url = winch_plate_data[$('make_drop_down').options.selectedIndex - 1]
                                .models[$('model_drop_down').options.selectedIndex - 1].url;
    top.location.href = "/" + url;
}