Good catches on all these small-but-important items, @eb801. You're going to have a really nice result.

As usual your attention to detail makes this one stand out. In my humble opinion this sort of attention is what makes all the difference - and as you said, you will know!

More Details: Upper Cooling Air Ducts
While I’m waiting for painted parts and the clay raft to dry, I’ve been taking a close look at the wings. I’ve already glued the top and bottoms together and inserted the carburetor air intake hood in place. AMT/Ertl paid attention here and molded a clunky approximation of the two upper cowl cooling vents, one on each side of air intake hood and each molded in the solid “open” position. They are quite chunky looking and not at all “open”. They are molded incorrectly and should be the same size on both sides.

I got out some tiny drill bits and excavated a series of tiny holes that I scraped out later to create an “open vent” look. Not sure if it's worth the effort but I think so. I'm not finished yet with these.

From what I have gathered, these vents were opened only on the ground after the engine was shut down to let hot air escape from the cowls. Most photos show these vents fully open.

Here's some more reference photos:

Here's a rear shot with vents in the closed position:

More Wing Details - Lights

Kudos to AMT for molding an outline for the wing formation lights. From late G models and on, these lights were relocated to the wing tips. I added a couple of applications of white glue to simulate the clear light bulb covers. These will be painted transparent later. Here's some closeups of the wing tips.

Now if you really want to get technical, A-20's also had formation lights at the very rear tip of the main wings. It seems they were deleted by the time of the A-20H.

Nice detailing with the white glue, Eric @eb801

You did great on the raft, Eric @eb801
It looks like it and is definitely visible from the front, a nice addition.

Red Roo Saves The Day!
After 18 days of no work on the Boston, the resin tropical cowl and nacelle replacements from Red Roo Models arrived all the way from Australia today. These are night and day difference in quality. Superb, crisp engraving and well molded in white. The original set they sent me had soft details, molded in shiny grey and the fit was useless - complete garbage. Somebody totally goofed up at Red Roo, but they certainly came through with this replacement set, so my hat's off to them for the excellent customer service and owing up to their initial mistake. The wait was well worth it. Now I can proceed to model an early production DB-7B/Boston III with those open cowl side vents.

Here's what the set looks like:

Nacelles Attached to Wing

There is no detail whatsoever in the wheel well so i used styrene rods to busy it up a bit. Total fantasy on my part but it really makes a difference even though no one will ever see it unless they turn the model upside down or stick a dental mirror underneath. Took me a couple of hours at most but I think it was worth the effort. The fit was fine.

Here's how I started out, using .75 mm Evergreen styrene rod:

Both wells painted and weathered:

The view from the outside:

The fit was fine. Here's the exterior of the Red Roo nacelle with the indentation for the exhaust stack.

Now it's time to attach the wings to the fuselage.