repeating task - not recurring

Been working with MS Project2000 for a few years and we recently upgraded to 2003 but I am still a novice - basicly self taught but I am only one at my place of work who knows how to work with MS Project. My question is that I often have certain tasks that are repetive(such as a outside process) but are not a recurring type task. Often the time span will change. Is there any way to change all of them at once instead of one at a time. Some of my project schedules may have several hundred rows and this can be quite time consuming looking for these tasks. I was hoping that where was a way like in excel to make a formula ( outside process = ?) or any other way.
Thanks in advance for any advice.
Bob