Soligor Flash

Hi there,
I've found a Soligor MK-6A flash in my bag of "Old" camera stuff, but i didn't found any manual (probably lost over the years).
I tried with my E-3 and only works in manual mode but it's ok.
The only thing i found on the net was the trigger voltage (38 Volts).
Does anyone know the Guide Number for this flash? I know it's more than 30 years old but if it has a GN greater than the one on the E-3 (has a GN13 flash) it may help me up for a few months until i go for the FL50R.

Thanks in advance
Chris