Various hardware needed to be attached to the end rib section. They will all be on the inside of the tank and riveted in place, so they are the first parts to get sealant applied.

It is hard to see, but in the first picture there are two small tooling holes. Left open, all the fuel would leak out. These tooling holes need to be plugged. Van’s has a simple solution, just put in a big rivet and seal it up. I did one and found the rivets way too long and they want to bend over rather than crush, so I used my rivet cutter to shorten the rivets a bit and they worked great.