Slow going but still doing this butt rib end. This end shows then 4130 spar plates and aluminium right angle that fixes the butt rib to the spars. What was difficult is the 6.5 degree sweep back because it means that getting a bolt on or a socket is hard as the rib does not sit at right angles to the spar. This meant a few false starts in passing bolts through and getting nuts on. Anyway rear spar is done. I have used AN 4 bolts for the through bolts, but perhaps could have used AN 3. Bolt dimensions not called out in the Delta plans.