Distributer cap replacement how often?

The "3-pak" looking distributer cap is the original with 75k on car. How often should this be replaced. I am experiencing a bucking every so often at highway speeds. I am replacing the plug wires and a new set of plugs also. From an old school mentality, I normaly would do the cap too, but this one is different.

can someone explain to me this. Does this car have what I call a distributer cap as I know it???????

On distributorless systems, even less maintenance is required. Since there is no distributor, there is no cap or rotor to wear out. The only normal maintenance required on these systems will be the spark plug and wires.
as described at
:)

http://www.autozone.com/servlet/UiBroker?ForwardPage=az/cds/en_us/0900823d/80/0e/f1/a5/0900823d800ef1a5.jsp