Just FYI, OnStar is now available aftermarket to all vehicles via 3rd Party rear view mirrors. They are available at Best Buy.
Personally I think it would be cool at first and handy in emergencies but I cant justify the cost /month because I can only think on one time in 4 years that I could have used it.
Onstar has several Tiers depending on whether or not you want vehicle diagnostics, directions and connections, stock and weather updates, Lojack-like tracking and a few other telematic services (I know from my sky I used to own). I liked the directions, the person just inserted the information, then the data is loaded onto your onboard computer and gives you directions. Similar to Sync, but Sync is currently free for the next 2 years. Not sure after that. I subscribed to just the lojack stuff and vehicle diagnostics. It was nice to see a report on how your vehicle is doing. You can also do the same with Sync, it's actually been a while since I've done that.
A cheap tracking system for your truck is an extra cell phone. Most plans let you get the phone for only $10.00 per month. And then you sign up for family locator and there you go. If you are parking in an area that you are concerned about, turn on the phone. To track it, you just log on the website and see where it's at.
Just remember to hide the phone. And it you expect to leave it there for an extended time, you may want to plug it in. Most vehicles have a power plug in the center console, or in the back of most pickups and SUV's . Out of sight.