Open folders 'techtree':

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Open 'tech1.tt' and find the following line:
fed_akiraZ.odf 1 fedU_chassis2.odf

add beneath it:
fed_aegianZ.odf 1 fedU_chassis2.odf

Find the following line:
fed_akiraY.odf 1 fedU_chassis2Y.odf

add beneath it:
fed_aegianY.odf 1 fedU_chassis2Y.odf

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Open 'fulltech.tt' and find the following line:
fed_akiraZ.odf 0

add beneath it:
fed_aegianZ.odf 0

Find the following line:
fed_akiraY.odf 0

add beneath it:
fed_aegianY.odf 0