Mori Seiki SL-150 drawbar length

We are having issues locating any information on the length of the drawbar for our Mori Seiki SL-150. The machine did not come with any part specification drawings or dimensions, other than the reorder parts lists. We had to retrofit a broken Doosan drawbar, which left the length a bit to long for the pullback collet chuck we use. What is the best way to go about measuring for the precise length needed if all else fails and there are no specs for the drawbar? We appreciate any feedback.