To open the Vertical Units Transformation dialog box, in Toolspace, on the Toolbox tab, expand Miscellaneous Utilities 
Drawing Transformations, and double-click Vertical Units Transformation.
Note: This transformation is only available for Montana imperial coordinate systems.
The Vertical Units dialog box transforms between International and US feet for Montana coordinate systems.
US Survey Foot to International Foot. Specifies the transformation to occur form US survey feet to international feet.
International Foot to US Survey Foot. Specifies the transformation to occur from international feet to US survey feet.