So this "Sales Item to Product" is the product type they have created in Dynamics CRM?
In GP we have default item types (we can not add any new type in GP). So if you are not using any of the other types than 'Sales inventory' is the type you should use.
whereas in CRM we can add new product type and make any one of them as default. By default CRM have 'Sales Inventory' type as default for Products (as what I see on my online CRM). So if you want to map GP 'Sales Inventory' to the new product type created in CRM, I think you have to make that type default or you just map 'Sales Inventory' type of GP to 'Sales Inventory' of CRM.
