I'm sure that it is possible to dig information about this capacitor or the part number coding. If it turns out to be hard, then you can find its aproximate voltage rating by lab testing. Use a series resistor, lets say 100 Ohms (for peace of mind), multimeter on mA range and slowly increase voltage on a lab supply to find where it starts to breakdown with leakage current suddenly increasing. If the capacitor was not used for some time, let it sit for a while at low voltage like 10V, so it rebuilds the oxide layer, otherwise leakage measurement could end up being confusing. It is not dangerous for aliuminum electrolytic capacitor to breakdown if current is small and for short duration. When you observe sharp change in leakage, call the test done, don't allow more then 5mA. The real voltage rating will likely be somewhere 30-50% less then measured breakdown voltage.
Edit: Not for high voltage or very high energy capacitors! Stay safe.