Generally speaking most engines have a 100k cam-belt change interval. By then they are well due for replacement! You gotta remember that they do a heck of a lot of work. Not all engines are "interference" engines either but those that are can be very expensive to repair iffen the pistons clout the valves. They are not all that hard to replace yourself either. The cheats way of by-passing timing issues is to use a stanley knife to split the old belt in half length wise (which makes them a very narrow belt), cut the front-most section through and remove. Then slide the new belt on as far as you can against the remaining old belt and use it to push the old belt off the back of the timing pulleys, cut through the old belt and remove. Cheers.
Derb. 2017 Colorado LTZ 4 x 4 Auto. 2014 Southern Star 720 and 1980 Zephette 340. 2 x 100 a/h AGM. 3 x 150w solar. Ctek D250S-Dual controller/MXS15 charger.172L fresh/grey. Diesel heat. RMD8555 fridge.