that is one of the things that makes the 2.7 so good...
Basically there are one of 3 things that take the drive from the bottom of the engine up to the top of the engine.
There is the CamBelt, which is a belt very like a fan belt, but with teeth on the inside of it, made of rubber/plastic substances that needs regular changing, as it is stretched very tight, and perishes in a relatively short time, and can then slip or snap.
Then there is a Chain, which is pretty much just like a bicycle chain, that does the same job as the cambelt, but being made of Metal, lasts longer. The down side is, over time the chain still stretches, and after a while it stretches so far the tensioner can't keep it tight. Then it starts to slap around, and wears it's self against anything it can hit, in some cases wearing holes in the metal work of the engine as well.
The third option, is what the T2's have, which is a series of cogs to bring the drive from the bottom of the engine up to the top, which basically can not stretch or snap, so nothing to change.
Have a night out on the the town on the money you have just saved...:lol