Step 1 : On the eCC Desktop dashboard, go to "Products > Synchronize Products", as shown in the picture below :
Step 2 : On the "Out of Sync Products" screen, click on "Display & Print Settings" option, as shown in the picture below :
Step 3 : Upon clicking the "Display & Print Settings" option, a new pop-up window will appear. Select the "Quantity In Orders" option and click on Save & Close button.
Now you can see the quantity of products, which are not posted to QuickBooks yet.