In the french community, the board admin have been post this screen when the server was in devlopment

Except it's not the same as the one we have on the actual server.

Sorry, not screen in my message.

I give the URL for the message

board.fr.ogame.gameforge.com/b…-old-school/#post13311328

Last screen at the bottom of this message

As I said, it's not the same ship. The one in the picture in the link you provided should have a much higher health than the one we have.

I just can't get over how the gamma glider seems like a gag ship.

The structural integrity is equal to the sum of the cost in metal and crystal, so that it will cost only 1.000 units of metal (or crystal, or a mix). Shield 20 means only crystal, i guess, because the shield is usually influenced by the ratio between metal and crystal.
The deuterim cost is usually due to rapid fire (5 vs probes and sats doesn't count), and sometimes to weapons and speed. the rf cost is 250 for each point, with some reductions if you have rf only vs one or 2 things and in other cases. Anyways for this slow, non-armed ship should be 0.
I've never understood how the cargo bay is influenced by the cost, but in general it seems to me that is not related to deuterium costs.

So (even if it seems weird to me), i'd bet on 1.000 crystal only.