What diameter is my crankshaft?

i have a 1997 Mitsubishi Montero Ls 4X4...im replacing a harmonic balancer because it wobbled and i want to make sure that it didnt mes up my crankshaft diameter because if the old one breaks for the same reason its not covered by warranty and i payed $140+ for this part so..please help ASAP i dont have a repair manual at all!...and i need answere like literaly ASAP cause i have no way to get to work today