I have a couple of speakers that have been kicking around my workshop for ages and i don't know what they are other than the small label on the back. They are 10JM251 15ohms, and 10 inches diam. I suspect the came out of a combi - hence the pair at 15ohms bit were they ever out of a Marshall unit? The JM in the label is what leads me to suspect this but I am not sure. has anyone ever seen this sort of label?