I finihed drilling it and glued with epoxy the 1/4" space that goes beween the 1 1/2" bars of 2024T4 that are use to fix the rear spar end !
Once the epoxy will dry out I will drill this with the #20 drill because there is a AN3 - 10 bolt that goes there .
Note the top corner that leaves a 1/8" space to give the longeron a place to sit flush with the vertical post. Note the 2 spacers of different thickness used to fill in space. Sorry for the picture , I tried to rotate it properly and was unable. It seems that since I moved on W10, pictures have a mind on their own.