Differential.

Differential at RC Shopper: 16 items in stock in the UK. Prices run from £2.99 to £45.99. Stock comes from Yokomo and MST. There are parts here for YD-2, but check the listing for the revision you run. This is all on the shelf, not on order from a distributor. Before 2pm on a working day means it ships that day. Check the part number against your own car before ordering; a lot of these parts fit one chassis revision and not the next.