It's hard to find a definitive answer on Michael's Kursk number. I have searched myself, at several sites. Like all Commanders, he had many tanks at his disposal.
In Russia, 1941 Operation Barbarossa, he was in a Stug3 Ausf A named "Buzzard"
As for his other tanks, S04 is the proper number for the 88 kill rings. This is the tank in the pictures with him and his crew (including gunner Bobby Woll)
Wittman commanded several tanks. This includes the famous 222 used at Villers-Bocage. His official tank, when he commanded the 2nd Company, was tank # 205 And his final tank, #007 in which he was killed in action.
If you need more info, try here:
http://www.panzerace.net/index.asp