12V Cummins Into An A Body
Not sure about an A-Body, but here is one in a 70 Monty Carlo.
My guess is that you would want a full frame under it.
[ame="http://www.youtube.com/watch?v=RO_kjaxIDzc"]1970 DMC Diesel Monte Carlo '99 Cummins turbo 24 valve - YouTube[/ame]
And a Chevelle
[ame="http://www.youtube.com/watch?v=KhgXSlEFncw&feature=related"]Duramax Chevelle 11.6 at 120mph - YouTube[/ame]