Sorry I do not have a caliper with me. Can't go to office to retrieve it yet since everyone's to work from homeIt will be difficult to make the clearance wider b/c doing so will reduce the side wall thickness. During CNC machining, the vibration from the cutter might break it the part if the side walls are not sufficiently thick.
There is suppose to be 120.8mm width. Can you measure your radiator width and the width of your chassis for me?
For now this is the best I can get: