The best and most comprehensive books I know & have about the T3 medium tank are :
- US Military Tracked Vehicles, Fred W. Crismon (Motorbooks, 1992)
- US Military Wheeled Vehicles, Fred W. Crismon (Motorbooks, 1983)
- Stuart, A History of the American Light Tank, R.P. Hunnicut (Presidio Press, 1992)
- Sherman, A History of the American Medium Tank, R.P. Hunnicut (Presidio Press, 1994)
- American AFV's of WWII, D. Crow/C. Ellis/P. Chamberlain (Profile Publications, 1972)
- US Armour Camouflage and Markings 1917-45, Steven J. Zaloga (Osprey Publishing, 1984)
- The BT2 Tank, part 1 (Armada Press, 1998) (Russian language, English captions)
The last one brings only few additionnal photos of the tank chassis.
Most of these books are now out of print and they're not by far dedicated to this specific tank, but if you're lucky enough to find them in second hand, they're really damn worth the money!
I hope this can help you!
Cheers from France!