Against infantry and what armor the Japanese had, the Grants worked well. However, everywhere else (Western Europe & Eastern Front), the Grants were no longer considered adequate. A big part of this was due to their likely opposition in those theatres. As a result, many of the surviving M3s were either converted to ARVs and engineering vehicles, or sent to the Far East, where the opposition was still considered manageable. In fact, I think the Soviets used some BT series tanks when they invaded Manchuria in 1945, again, due to the fact that they had them and that those vehicles were grossly outclassed everywhere else.