Ok here's some info to straighten things up if you're confused. The 10 degree rotation will "clock" your transfercase 10 degrees so it will sit "sideways" somewhat. This would require a specific dual case crossmember built for the 10 degree rotation which will give you more clearance under the crossmember.

A forward shift transfercase's shift rails come out of the front of the transfercase and the shifter base is located on the transmission whereas a top shift transfercase shifter is directly mounted to the top of the transfercase with no external shift rails. My transfercase is forward shift ( well now technically the crawl box is forward shift) The front case can be either forward shift or top shift depending on the model of your truck, but the rear case must be a top shift. There are conversion kits for forward shift cases to make them top shift cases if you cannot find a top shift case.

And the twin stick is as explained above. The only reason you'd need a twin stick set up is if you had an auto front locker like a Detroit locker. Other than that, there isn't much need for one...

Here is my short buildup thread on my dual cases I built, it may clear some stuff up for you also...

https://www.yotatech.com/forums/f116...-cases-186883/