2 hrs. working on the fuel cap and drain fittings.  Also a second fit of the right tank back plate to the main spar.

Traveling for work for the next 3 days, so I'll be back at it on Friday.

The locking fuel cap doesn't fit in the parts as they come...

Time to grind them down.  Here I have both the left and right upper parts to grind them together.

Used my Dremel with a mini ScotchBrite wheel.

The lower (inner) ring part needed a lot of grinding...

Voila!  Perfect!

And on the tank.

Test fit of the back plate with the bolts into the nutplates.  All lined up!