Again about aft joystick mounting...
I eventually was lucky and found, in another very huge collection of original photos (at the
Library of Congress website), a nice photo taken at a low angle in the aft cockpit, showing the RHC assembly from a new point of view
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Since this photo was available for download in a really HiRes format, I was able to focus on a single detail that was the one I was searching for.
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So I now have a better idea about what is behind the corner

In detail I had confirmation that there is a sort of tube connecting the joystick box to console side wall.
Having this photo as a reference I draw a whole new detail using the same "layers" technic as for the joysticks.
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And this is the final assembly
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And now the aft section is really complete.
I'm so satisfied with the result that I dare to show it side by side with the real Endeavour !
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!!!!