This module allows you to import your orders from OsCommerce to ShipStaion for easy shipping – including creating shipping labels, sending shipping confirmation emails and comparing shipping rates for most of the North American couriers (including Canadian carriers: Canada Post and Purolator).
No core files changes are required – just adding one file and completing the setup from ShipStation.
Tested on 2.3.4 BS EDGE - should work on any version of 2.3
Support thread here;
https://forums.oscommerce.com/topic/412291-shipstaion-for-oscommerce/