The bottom of the post is drilled and tapped and a bolt runs through the DS and into the post on mine.
I removed the end caps by drilling out the 2 rivets on each and prying them off with a screwdriver very slowly and carefully so that I didn't scratch or nick the cap. To get at the bolts for the DS I had to remove the outboard hull mounting bolt, and then had my 10 year old stick his arm in there with a wrench to hold the nut in place. It went pretty good. I hope you have a 10 year old, or really skinny arms. I used nylock nuts .