having trouble getting malformed JSON cross-domain

Question

This is a very narrow scope of the code, but it is where the issue lies.

function getJSON(tabUrl){
  $.getJSON(tabUrl, function(data){
    console.log(data);
  });
}

I am using jquery 1.3 because getJSON in 1.3 can handle malformed JSON. The server I'm getting my json from uses the old parameter:'value' format.

Here is the perplexing issue.

If tabUrl is a cross-domain server and is valid JSON, it works fine.
If tabUrl is a local file and is either valid OR INVALID it works fine.
If tabUrl is a cross-domain and is invalid I get no errors in firebug but cannot manipulate the data.

I have no problem using jQuery 1.4 if there is a workaround someone can propose.