is there a precise list of elements to add to a Brat model to transform it into a Scout?
Scout components:
]Lexan Components (BT-03)/:m]
]5x Aluminum “C” Servo Bracket with Ball Bearings Two Pack (ASB-09) /:m]
]2x Aluminum Multi-Purpose Servo Bracket Two Pack (ASB-04) /:m]
]2x Aluminum Dual Inline Multi-Purpose Servo Bracket Single Pack (ASB-15) /:m]
]1x Aluminum Long “C” Servo Bracket with Ball Bearings Two Pack (ASB-10) /:m]
]1x Aluminum 15-degree Ankle Bracket Two Pack (ASB-17) /:m]
]1x Aluminum Robot Foot (Pair) (ARF-02) /:m]
]1x E-Z Aluminum Servo Bracket (One Pair) (ASB-02) /:m]
]1x SES Electronics Carrier (EC-02) /:m]
]12x Hitec HS-5475 or 5645 servos (standard sized and powerful)/:m]BRAT components:
]3x Aluminum Multi-Purpose Servo Bracket Two Pack (ASB-04) /:m]
]3x Aluminum “C” Servo Bracket with Ball Bearings Two Pack (ASB-09) /:m]
]1x Aluminum “L” Connector Bracket Two Pack (ASB-06) /:m]
]1x Aluminum Channel - 3" Single Pack (ASB-503) /:m]
]1x Aluminum Robot Foot (Pair) (ARF-01) /:m]
]1x SES Electronics Carrier (EC-02) /:m]
]6x Hitec HS-422 servos (S422) /:m]
You’ll also need electronics such as the BotBoarduino and the SSC-32 servo controller, battery, charger and any other items you want to add.
I already have a complete Brat with servos, battery and Botborduino
That’s the list I had copied and compared but it looks so different.
A Scout is a complete different design? not some kind of extension of Brat?
The scout is a different beast, as you indicate, “not an extension of the BRAT”.
There is no upgrade package since quite a lot of the parts are different.
That’s my fault so. When I bought my Brat, I thought I’ll upgrade later if it was a nice product.
It was… so I have to think about my next Lynxmotion product carefully in terms of upgradability 
The bracket system itself is all based on the Lynxmotion SES system, so you can likely make a slightly modified version of the scout if you want to re-use some of the BRAT’s brackets and servos.