Upgrade of module from Drupal 6 to Drupal 7

Hello

I'm upgrading module (uc_deliverytimeslot) from Drupal 6 to Drupal 7.

But I'm not able to get deleivery_timeslot radio button value on checkout form while i'm getting other value in $order object but not getting delivery_timeslot radio button value.

From Drupal 6 version(uc_deliverytimeslot.pages.inc).
$data = '';

so what should i need to do change for Drupal 7 here.

Kindly suggest me!

Thanks in Advance!