Vacuum advance cover mounts over your factory unit with two sided adhesive. GM HEI cap cover snaps over top O.E.M. wire retainer.
 
Part # ProductMaterial Media
9090 GM HEI Ignition Cap "Cover"- Chrome Steel
Photo
$10.67
4973 Vacuum Advance Cover- Chrome Steel
Photo
$4.84
 
http://hedman.com/images/ePIM/original/9090.jpg
http://hedman.com/images/ePIM/original/4973.jpg