Ammo GUI Display Bottom Right of Screen?

 var bulletHudTexture : Texture;
 var ammoCountRect : Rect = Rect(25,25,50,25);
 var ammoStartX : int = 100;
 var ammoY : int = 25;
 var ammoSize : Vector2 = Vector2(2.316,15);
 var ammoSpacing : float = 3;
 var ammoDecorationHudRect : Rect = Rect(25,50,50,25);
 var ammoDecorationTexture : Texture;
 
 function OnGUI ()
 
 {
 
     if (beingHeld)
 
     {        
         if (ammoDecorationTexture)
 
             GUI.DrawTexture( ammoDecorationHudRect, ammoDecorationTexture);
             
     for (var i : int = 1; i <= currentClip; i++)
     {
         GUI.DrawTexture(Rect(ammoStartX + ((i - 1) * (ammoSize.x + ammoSpacing)), ammoY, ammoSize.x, ammoSize.y), bulletHudTexture);
     }
     GUI.Label(ammoCountRect, currentClip.ToString() + "/" + currentExtraAmmo.ToString());
     }
 }

How do I use Screen.height and Screen.width to make the GUI in the bottom right corner instead of the top left corner.