Summit GPS reading

I often will take a shot of my GPS at what seems to be the highest spot on a mountain. This is a Magellan Sport Trak pro although I also use a Garmin 60CS on some hikes. This GPS has served me well since 2002, despite being dropped and unintentionally abused. I like this model so well that I found another which I have reserved as a back up for when this one finally bites the dust. I like to use the lat/long nad 27 or nad 84 datums.