I bought a Garmin Montana 650T this spring and used it at Moab and in the Cascade Mountains. After struggling with the Garmin website in trying to figure out what mount to buy. I sent an email to support at Garmin and got the airhead response that I should pick one from their website. When I replied back that I had not been able to decide from their website which mount was appropriate for my application which was why I had written in the first place, then someone higher up the feeding chain answered that probably none of their mounts would work for my application and that I should look at RAM.

I have been very pleased with the RAM mount (and the Garmin receiver).