1. outer wheel can run freely, full power to inter wheel
2. no only if you use both one direction in both front and rear, yes I seen one before..
3. see two difference hong kong brand before
please someone correct me, think like a little bit wrong.
A ball differential is rare and expensive in ebay or yahoo jap. I have never seen the one way in the auctions (maybe it is only local made as mentioned by brother fat_fat_cat). If anyone got this item, please post a photo here.The old advertisement on 遙控模型 is also requested.