OK-UZB was the third L-610 prototype and was primarily used for stress testing. This photo was taken at the museum's previous location at Olomouc. During the 2015-2016 period, the museum was forced to leave their Olomouc location. Eventually, they re-established themselves at a new location at Koněšín.

In total nine prototypes of the L-610M were produced; six for flight testing, two for static testing and one that was unfinished. X03 underwent trials at VZLÚ (Czech Aerospace Research Centre) but after cancellation of the L-610M program it was used for some L-610G tests. After the definitive end of the L-610, X03 went to the museum at Olomouc but is now on display at Letecké Muzeum Koněšín.