For most 240 owners the HT leads have lost their original retaining devices. i always use Volvo leads as they are high quality and have the correct ends as well as being the correct length. The Volvo leads come as a set of 4 - the King (coil) lead comes seperately (always ask for both) as the coil's position changed during the production run resulting in different length leads.
Starting from the distributor cap they go into a circular retainer. This should be positioned close to the manifold - without this there is serious risk of the leads rubbing against the manifold (there is a sharp edge). I have seen a fairly new lead short out because of this. Next there is a clip holding it onto the cam cover with a second one sat on the cover:
There are then two clips bolted on to the cam cover holding the leads for cylinders 1 & 4. This enables all leads to be securely held without risk of touching each other or rubbing against any part of the engine:
This will help ensure that your HT leads stay in optimum condition for as long as possible as well as keeping the engine bay tidy.
All these parts are still available from Volvo and are not expensive. The plastic clips are a seperate part from the metal holder.
Mike