Table schema:
CREATE TABLE table_13643320_2 (rnd VARCHAR, gtp_winning_team VARCHAR, gto_winning_team VARCHAR)

Question: What us the number of the round during which #56 Blue Thunder Racing become the GTP winning team and #38 Mandeville Auto Tech became the GTO winning team? 
SQL: SELECT rnd FROM table_13643320_2 WHERE gtp_winning_team = "#56 Blue Thunder Racing" AND gto_winning_team = "#38 Mandeville Auto Tech"