How to add featured image to other post types.
ADD TO THEME FUNCTIONS
// This theme uses post thumbnails
add_theme_support( 'post-thumbnails', array( 'plans','listings','news','post' ) );
ON POST-TYPE SPEC
'supports' => array( 'title','editor','excerpt','thumbnail')
ADD TO LISTING
$themeurl = get_template_directory_uri();
$link = get_the_permalink();
if ( has_post_thumbnail() ) {
echo '<a href="'.$link.'">';
echo get_the_post_thumbnail( $post->ID, 'thumbnail', array(
'alt' => trim(strip_tags( $post->post_title )),
));
echo '</a>';
} else {
echo '<a href="'.$link.'"><img src=" '.$themeurl.'/images/planblank.png " alt="no image"></a>';
}