FRANKFURT, Sept 29 (Reuters) - The chief executive of Volkswagen"s (VOWG_p.DE) truck unit Traton (8TRA.DE), Matthias Gruendler, will leave the business and will be replaced by the head of Traton subsidiary Scania, Christian Levin, who will lead both businesses. In a statement late on Wednesday, Traton also said that Traton"s chief finance officer Christian Schulz will leave alongside Gruendler. CFO Schulz will be replaced by Annette Danielski, currently Traton"s head of group finance. Traton said the management changes, taking effect on Thursday, were decided by its supervisory board, chaired by VW non-executive Chairman Hans Dieter Poetsch. The company did not provide reasons for the moves in its statement.