Well, height and length does mean everything (for the most part). Best case scenario would have my antenna on the top of the truck, but then I would have to get out and fold it over to pull into my garage.
The basic rule of thumb is the longer it is the better it is provided it is a length that is 1/4 wavelength, 1/2 wavelength, blah blah blah.
Gets a little complicated.

@h3humvee- I used a lo boy mount that I bought at HRO. here is a link to the manu: http://www.pro-fit-intl.com/loboy/

They have a bunch of different options, all using adhesive tapes for easy removal later. My knee can hit the rigs face at times but I can actually move it over more towards the center of the console by another 2 or 3 inches, I just havent got around to it yet. The speaker is totally out of the way and the rig body is under my drivers seat.
It looks kinda tight (and it is) but its also hard to see from the outside of the truck

The only bad part about it is that I wear polarized sunglasses so if I dont look at the display at the right angle, it vanishes. A lil annoying sometimes.

Yep the 706 is a sweet rig- Kinda cool cruising around and talking to places like South Africa when conditions are good

Anyone intersted in Amateur Radio should visit http://www.arrl.org. That will get ya started!