If you don't have a dash panel in your vehicle, this mounting cup may be the answer. The base can be screwed down to a panel or tube, or hose-clamped to a tube. The cup pivots nearly 90 degrees to adjust the angle between the cup and the tube. It does not swivel, so the tube will be parallel to the cup (in other words, you cannot clamp this mount to a dash cross-bar -- the gauge will point to the side of the car and not to the driver). Accepts most 2" diameter gauges*.
Note: Fits all 2" Auto Meter gauges. Some other gauge brands may require some modification to the mounting cup.