Some of us are long out of the military and are not "up" on who is flying what these days. It would be a great help for us if you were to remind us what country(s) is/are using the named aircraft. Other than this, I found this an interesting bit of information.
the SU-37 is being used by the russian federation air force but its only a prototype aircraft and only 2 were built but indeed a impresive aircraft it most likly could out manuver and shoot down a F-15 but, theres the SU-PAK FA it is the russian equivilent to the F-22 the PAK will use current developements in the SU-47 A.K.A. S-37 and the MiG 1.44 but the SU-37 like other closing soviet programs like buran never really got to be used in sevice
I believe that the vectored thrust feature of the SU-37 was first developed by the U.S. It was never included on U.S. figher aircraft, to my knowledge. It's interesting how much technology developed in the U.S. ends up in Russian aircraft. As to how many SU-37s have been built, we only know what the (former?)Soviets tell us and they are not always truthful. :-) They could be in serial production and we would not know it until our pilots faced them in combat.