What version are they running now?

You may be able to take the shipping modules from v1.3.7.1 and use those ...
http://www.zen-cart.com/forum/showthread.php?t=69769

Be sure to backup your files first ...

On older versions you will need to edit the shipping modules, for example, on USPS you need to change the line:
PHP Code:
class usps extends base { 
to read:
PHP Code:
class usps {