Might be very helpful to have the complete model # & serial number of this Komatsu. The full model # like FG25ST-12, etc will help ID the design series & the s/n will help to ID any changes that may have been mode for that design series. The mast was more than likely built by Cascade or LiftTech. The ST series is primarily sold in the N.American market (mainly US). It is a press-on solid machine (S) indicates that. There should be stamped on the mast a model & s/n too (very helpful if the mast was ever switched or if the chassis was originally shipped w/o mast).