From Tanks in Detail #2, M3-M3A1-M3A3 Stuart I to IV, by Jonathan Forty:
"The M3A3 was produced almost exclusively for Lend-Lease and saw service with the British and Commonwealth armies in Italy and northwest Europe and Asia, as well as with the Soviet and Chinese armies."
I have been unable to locate any text or photographic evidence referring to US use of the M3A3 other than the prototypes or tanks used in trials before approval for manufacture.
Sorry...