"January 9th, 1938
1st Department of factory #37
To the Chief of the ABTU, Corps Commander Pavlov
CC: Chief of the 8th Main Directorate of the NKOP, Brigade Engineer Sviridov
RE: engine and armour for the amphibious tank
ABTU letters #184910s dated December 11th, 1937 and #183939s dated October 26th, 1937, state that the 6-cylinder Dodge engine must be used in the amphibious tank that is under development and the armour should be made in two layers, 3+7 mm, preferably at an angle.
On December 31st, 1937, you stated that the Dodge engine is unsuitable for the specified tank as it is difficult to tune, wears quickly, runs too fast (3600 RPM), and is supercharged. We designed the tank's transmission for the Dodge engine according to ABTU requirements (see above letters). We ask you to give concrete requirements on the type of engine to be used in the tank. A replacement engine with a different RPM and power will require a change in the transmission, which is why you must reply urgently.
We do not think that it is rational to prepare the experimental Dodge engine present at the factory right now, as serious changes to the transmission that an engine replacement will cause significant delays in working out prototypes.
We are not familiar with the design or methods of attaching two layer armour and request necessary materials based on which we could design a new hull for the tank, or directions on where these materials could be obtained.
Sloping the armour will result in serious complications in the design of the hull and all attachments. Minimal valuable slope needs to be specified. Initially we planned to make the sides slope at 20 degrees and 0 degrees. Please confirm if you agree that this is sufficient and accept the complications introduced in production.
The aforementioned letters specify that the armament of the tank is one DT machine gun. However, you say that a new heavy machine gun needs to be used.
We ask you to tell us the weight of the new weapon, send blueprints for designing a mount, and also specify if the new machine gun replaces the DT or if the new weapon is to be installed additionally to the .30 caliber machine gun.
Factory director Shor
Chief engineer Kozyrev"