Short night tonight. I fabricated the two 3/8 OD x 1/4 ID spacers that go between the two center section bulkheads. Here's a trick for getting the ends nice and square. Chuck them in the drill and hold the drill up to the side of the scotchbrite wheel while both the drill and the wheel are turning. Makes it easy to get the end nice and square.

They're supposed to be 1 7/16 long and low and behold, they are!

Update: I didn't need to fabricate these after all. I found them already cut to length elsewhere in the parts pile. Oh, well.