Chrysler
   

Ford
     1976-77 Simplified Wiring Diagram for an LTD, Cougar and Thunderbird with a duraspark box.
   Here is a good reference site for 351M and 400 cubic inch engines:

GM
    The Cadillac Engine Guide, Courtesy of the Caddy Shack.  Nice information on 472/500 blocks.

Foreign 

Other
 Trailer Wiring Diagram