Q: What are the outside dimensions of the GDU 450 unit so that I can check panel space?
Per the Garmin manual the dimensions are 10.85W x 7.82H
Q: Is this Garmin G3X GDU 450 IFR certified?
No, the GDU 40 is an experimental only display. When paired with an IFR unit, such as the GPS175/GNX375, GTN 650/750, GNS 430W/530W, GNS480 and GNC255, the GDU 450 can display CDI information for IFR approaches.