Pete, The OEM external HEI coil used two of the side cover bolts to mount. The side cover bolts were not the usual they are double threaded(?). That is they are threaded on both sides of the hex head. here is a to another discussion on external HEI coil;

http://www.chevytalk.org/fusionbb/showtopic.php?tid/262533/

Hope that helps.

Larry


Ignorance can be fixed Stupidity is forever