When listing the catalog, an associated version is included with each item/variation. How can I get previous version numbers of the specified item to go back in time (such as checking for previous stock history). Where would I be able to retrieve the previous version numbers?
Hey! 
When passing a catalog_version into ListCatalog, it will return objects of the specified or lesser version. That means if you want to retrieve the version prior to your current one, you can decrement the catalog_version by 1 in your request to get the next closest lesser version.