One of the interesting things that I noticed with the Link trainer our museum is restoring is that, in contrast to the wood example we have on display, its desk is made of metal. This made me look at Link trainer desks in more detail and it made me realize that there is some variation between them.
Some, such as this one in use at RNAS Lee-on-solent, have only a single fold-out drawer on the left side containing the radio control chassis:

(Source:
Wikimedia Commons)
Another one of this design in use with the USAAF:

(Source:
Air Force Historical Research Agency)
This picture is from a 1938 issue of the
Wonders of World Aviation magazine, indicating that this version predates the war:

(Source:
Wonders of World Aviation)
A different version:

(Source:
Planes of Fame Air Museum)
Others, such as this one at the World War II Flight Training Museum, have two drawers on the left side and a slide out surfaces on both sides. Note that this example is claimed to be original to the airport in Douglas, Georgia, potentially dating the usage of this version:

(Source:
World War II Flight Training Museum)
This one shows the characteristic curved edge to the surface of the desk and separate corner pieces (silver) of the one under restoration at our museum. Note that, in contrast to some of the other types, the handles on the drawers are open on the top as well as the bottom:

(Source:
AVADirect)
Here's a picture of this type in use in February 1943, again providing evidence that it is at least not a postwar design:

(Source:
Wikimedia Commons)
Still others, such as this one at the Delta Flight Museum, have a set of three drawers on the left side and the radio control chassis in the middle. Given the similarities with the ones below (e.g. row of holes on the lower drawers) and the fact that there appear to be patches at the mounting points, it may be that this is a 1-CA-1 with the gantry removed:

(Source:
Delta Flight Museum)
Finally, some, such as the 1-CA-1, have some sort of overhead gantry with a radio range quadrant attached:

(Source:
eBay)
Again, this time being used by WAVES at NAS Memphis in 1948:

(Source:
Naval History and Heritage Command)
EDIT (22-01-24): Thanks to a copy of T. O. No. 08-25-1, provided David D. Jackson of the website
American Automobile Industry in World War Two, I can now identify that the type of desk with the single fold out drawer on the left is for the C-2 and C-4 models. The metal desk - the one with the open top handles - was used for the C-3 and C-5 models. Although not illustrated, later C-3 models are stated to "use a wood desk similar in design to the C-3 and C-5 metal types". Presumably, this refers to the examples with the closed top handles. Being an AAF document, the desks used by the 1-CA-1 types are not mentioned.
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