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Not a GPS, but I've attached my PogoAlert that way:
I now have a new PogoAlert version but using the same cabling down behind the dash. The block is a receiver for something else unrelated.
I cut neatly the plastic so not to squeeze or force the connections - It would be a cheap part to replace if needed.
^ It's a good position to have such a device (providing it's not huge!) as it's directly in line with your vision while driving.