I ordered a diff drop from SuspensionMAXX but not sure it really helped much or was even necessary. Cognito is one of the best brands in the business and if they didn't feel like a small diff drop was needed, then maybe it wasn't. I did it for piece of mind, but again, it barely helped my CV angles. Probably less than 1/4" but some will say every little bit helps.
Also, on the 1" rear block, I think our trucks come with a 1" block already in the back. At least thats what Cognito that told me. Because i ordered 1.5" rear blocks and they told me i'd only see a 1/2" lift since it already had 1" blocks from the factory. Maybe someone else can confirm the rear blocks