Nice, have no clue.
I have seen a lot of mustangs and own a government 380 but have never seen one like that, I would assume it is from the transition period between the government and the mustang and used a slide that may have already been stamped with the government model roll stamp. But i'm just guessing, dont know what kind of value it could bring but i doubt much more than than a standard government 380 but it is unique
I sold one that was NIB on GB on a $.01 no reserve auction about a year ago. It sold at about $900. I find there is very little interest in factory error gun selling at more than the normal value.
thanks for all your responses, i googling without any clue but now i breathe again. CJS57, do you have mafg date?