We more than likely do not have to tell you that the EZGO Drive Belt for 89-91 Marathon models is a high-wear item. You know as well as we do that it rides between the sheaves on both the primary and secondary clutches. The front clutch pulls the belt higher and higher with eccentric force as you ride your golf cart. As this happens, the belt gets pulled deeper into the secondary. All of this friction wears down on the sides of the unit. An excellent way to tell that you need a new one is if it sounds like a dog barking when you take off. This means the belt sides are smooth and skip on the sheaves. If you hear this sound, it's time for a new one.This golf cart belt measures 41 inches O.D. Don't let that confuse you. Math class tells you to refer to that acronym as "outer diameter." This is not the case in this industry. That refers to the "outside dimension," otherwise known as the circumference. If this is the one you need, please get it ordered from Buggies Unlimited today.