Hey Jeff!
The trike is called : the MTC-18 (Motor Tricycle) and was built by Indian Motocycle Company. In total an Army order for 25 trikes. They received the order on April 4th 1940 and started the production immediately. The total cost was $25,500.
The MTC-18 is a "high power tricycle for Army purposes" and was built based on the Model 340 (the military 74 cu in Chief) - look at the leafspring front fork and frame! The manual for the MTC-18 bears the reference M634 (Feb 11, 1941).
In the background of picture #1 a Model 340 with sidecar can be seen.
The other "official" trike made by Indian is NOT a "servi-car" BUT the "Dispatch Tow" (DT in the Spare Parts lists), with 45 cu in Sport Scout engine. The "servi-car" is an exclusive name for the H-D built trikes!
H-D presented also a "high power trike" to the US Army: this was a prototype using a 74 cu in "Knucklehead" engine and special configuration.
Both trikes were suspended after trials because the Army choose to make use of the "Jeep" - presented by Willys-Overland.
Martin "Martinski"
Author of the book: "An American in Paris, the Story of the Indian 74 Model 340..."
www.indian-model340.be