The rear axle seperate from the frame. Axle is ENV-type as opposed to a Salisbury unit. All very early xk120's had this type. I am not sure why they changed to the Salisbury unit later. It might be that as a one piece casting as compared to the three piece of the Salisbury unit, that it was too expensive to manufacture. Both types are very durable. I will find out if this particular one is soon.