All of them are clutch type. I heard they put the Torsen in some of the 91 cars but never actually saw one. The Torsen we use in the ITS cars is actually a Miata unit. I think I have one on a shelf somewhere. Keep in mind that the ring and pinion from a first gen RX7 fits the 1800 Miata case. Off the shelf gears are 4.88, 5.12, and very hard to find 4.6 and 4.44 that were old RX3 gears.