[kh99]

No, just the one change, like this:

if ($_POST['do'] == 'updateprofile')
{
	$vbulletin->input->clean_gpc('p', 'userfield', TYPE_ARRAY);

	$fieldcontentbefore = array(
		'aaa',
		'ccc'
	);

	$fieldcontentafter = array(
		'bbb',
		'ddd'
	);


	$vbulletin->GPC['userfield']['fieldX'] = str_replace($fieldcontentbefore, $fieldcontentafter, $vbulletin->GPC['userfield']['fieldX']);
}

Where you replace the 2 occurrences of 'fieldX' with the real field name that you want to change.

Originally Posted by Simon Lloyd

It wouldn't be $field1 but rather ['field1'] so the id of the field you are trying to manipulate

Right. Or else you'd need to set $field to something like:

$fields = array('field4', 'field7', 'field8');
foreach ($fields AS $field)
{
    	$vbulletin->GPC['userfield'][$field] = str_replace($fieldcontentbefore, $fieldcontentafter, $vbulletin->GPC['userfield'][$field]);
}