Generally such parts use 'in-house' numbers, which means there's no datasheet or information available, as the number doesn't actually exist.
Someone like Magneti Marelli will approach a number of different manufacturers and ask for a transistor to meet a certain specification, the manufacturer will provide the devices with any number MM request on it, so it has no bearing on any transistor number from that manufacturer.
So no datasheet, and the only place you can buy them (if you can) is Magneti Marelli.