In an effort to warm relations with Washington, the Kremlin shipped an engineless T-34 hull to the United States as an "agricultural tractor" in late 1940. The Project was kept classified as the Roosevelt administration wanted to avoid criticism of engaging the Soviets, particularly in light of the hostility to Spanish Civil War Lincoln Brigade veterans and other 'premature anti-Facists'.
An 800 HP Packard 3A-2500 V-12 liquid-cooled aircraft engine (descendent from the World War I-era Liberty L-12) was installed, along with a single dry-plate clutch, matched to a floor-shifted three-speed manual transmission and a new one-piece driveshaft.
Slight modifications to the original turret race were required to fit the M3 Lee's turret.
Page allegedly taken from a declassified performance report, dated 31 October 1941.
Purported to have been taken at Aberdeen Proving Ground, late 1941. In addition to the 37mm M5 main gun, the T3A4 could mount three .30 M1919 Browning machineguns (hull, co-axial and commander's cupola). Only the Commander's Cupola weapon was mounted on this prototype.
Random unclassified comments by crew, mechanics and evaluators indicated that the mating of inch-pattern drive train and turret components to the metric hull were problematic.
The original vehicle is (apocryphally) said to have suffered an engine fire in 1943/44 and the hulk used as a hard target.Comments in the subsequent Aberdeen evaluations of a complete T-34 and KV-1 might give some indications of why the design was not pursued.
http://www.tankarchives.ca/2013/04/aberdeen-t-34-and-kv-1-test.html?m=1