Basic preparedness and safety takes just a little thought and a few minutes, and you will have the basic emergency gear stashed behind the seat or in the toolbox, you might need if that drive in your truck takes a bad turn. Here is what I think are the basics you should not be driving around without.
Can you and should you have much more? Yes and probably, but these things I am going to list cost little and should be there.
1) Your cellphone. Goes without saying that this is your lifeline. In today's world we usually all have them with us... just make sure when you leave you have it and it is charged.
2) Flashlight. No vehicle should be driving around without a flashlight inside. Spend a couple bucks more and get a LED flashlight so you can get hours of use on one set of batteries. An extra set of batteries in a plastic bag is a good backup as well.
3) Jumper cables. Again, no vehicle should be driving around without a set of jumper cables. Have them and know how to use them. These could help you or someone else get unstuck.
4) Fix-a-flat. These are several brands of tire sealer on the market and for about 8 or 9 bucks, you can have a can in your truck. This might make the difference between changing a tire in adverse conditions, or being able to limp back to a better location.
5) Basic tools. Lots of truck people are driving around with massive amounts of tools in their toolbox, but if you are not one of these drivers, this is what you need to do. Go to one of the bigbox hardware stores and get a basic tool kit in a plastic carrying case for under $25. Will it have everything you need for every situation? No way, but at least you have a chance for the basic emergencies
6) Coat or jacket. You have an old one you don't wear anymore somewhere in your house hanging in a closet. Get it an put it in your truck instead where it can be of use if you were to need it. An old blanket works well in this capacity as well.
7) Raincoat. Get one and stash it in your truck. A cheap plastic poncho is also good... Or at least a plastic trash bag you can put a hole in for your head and now you have a poncho.
You are driving a truck so by default you have lots of storage space to stash these items. Behind the seat, under a back seat, in the toolbox, and so on. Buy a cheap plastic portable toolbox, get the items on the list and put them inside, find a good storage spot in your truck, and now you are ready for most of the minor emergencies that may befall you as you truck down the road.
Can you get more gear for emergencies? Sure, and it is a great idea whose limit is only up to you. Flares, road reflectors, tire pressure gauge, jacks, foul weather clothing, lighting, compressors, emergency radios, and on and on. It is all up to you and your comfort level. But all the items above can be had for way less than $100 if you don't already have them, and might make a bad situation safer and easier for you and your passengers.
Let me add, that I have never lived farther north than central Texas, so I have no practical experience with harsh winter driving conditions. I feel sure there are things that y'all northerners keep in your trucks to be prepared in the winter. Feel free to comment and educate me on this!