Custom Fields and Custom Write Panel

if you make the $key the same as your old custom field $key it will be using that to show in the metabox.

$key = "key";

Thanks for the quick response.

I thought that the variable $key at the top of the script was only being used to label the write panel?

I am using the names of the custom fields I already have defined as the same names in the array to define the custom write panel fields.

For example, I have a custom field called thumbnail.

So in my array, I have:

$key = "key";
$meta_boxes = array(
"thumbnail" => array(
"name" => "thumbnail",
"title" => "Thumbnail",
"description" => "Enter the Thumbnail URL.")

Are you saying that the $key value should be thumbnail?

I just read they store their $_POST data as a serialized array.
in this tutorial they save the $_POST data as individual custom fields: https://www.deluxeblogtips.com/2010/05/howto-meta-box-wordpress.html
Just remove the prefix from the custum field key (id) to let the metabox use your custom field key:
so this:

'fields' => array(
        array(
            'name' => 'Text box',
            'desc' => 'Enter something here',
            'id' => $prefix . 'text',
            'type' => 'text',
            'std' => 'Default value 1'
        )
    )

will become this:

'fields' => array(
        array(
            'name' => 'image',
            'desc' => 'Enter something here',
            'id' => 'thumbnail', // your custom field key
            'type' => 'text',
            'std' => 'Default value 1'
        )
    )

I will give that a try thank you!

Works great thank you!