[Dylanblitz]

Give this a try, not 100% sure but it should work

if ($_REQUEST['do'] == 'editthread' AND $threadinfo['open'] != 10)
{
$vbulletin->templatecache['threadadmin_editthread'] = str_replace('{vb:raw posticons}','		<fieldset class=\"fieldset\">
	<legend>{vb:rawphrase redirect_threads_to_url}</legend>
	<div style=\"padding:{vb:stylevar formspacer}px\">
		<div class=\"fieldset\">
		{vb:rawphrase redirect_threads_to_url_link}<br />
		<input type=\"text\" class=\"bginput\" name=\"isurlredirect\" value=\"{vb:raw threadinfo.isurlredirect}\" size=\"50\" maxlength=\"250\" title=\"{vb:rawphrase optional}\" />
		</div>

	</div>
</fieldset>
		
{vb:raw posticons}',$vbulletin->templatecache['threadadmin_editthread']);
}