According to the book "Red Stars No4" by Geust, pg 196 "Only a handful of Kingcobras joined the VVS regiments in the European Theater. Six GIAP received 6 A/C in March 1945 used by 67 GIAP in the Berlin operation. Note: In this book there are photos of P-39's that were fitted with 4-bladed props so one must be careful in the ID of P-63's in Europe. The shape of the vertical stabilizer would be the key item to confirm aircraft type.