I know what you mean with the GPS units. I have an older Garmin GPSMAPS60CS, no memory slot. Detailed turn by turn, POIs, gas, food and other information that's very useful is on a separate disc that you have to purchase. You can usually find the units and or software cheaper than MSRP, if you take the time to look around. I purchased the additional software for just over $100 from amazon. As for the mount, I went with the Ram mount because it's cradle is specific to your unit and holds it firmly and not a universal type mount. Check out ram mounts and you'll like the options that are available. Oh and yes, the u-bolt will fit on the grab handle as I have the same mount with a different cradle.
Also I fount out the hard way that Garmin mounts are somewhat useless. Buy a real mount, like the one below. If you decide to use it on your boat, buy a base unit and move the rest of it around and no need to buy a separate mount for both.
*click on link for website
