Another vote for maintenance being the big one.
Almost every time one of my buddies has been broken down on the trail it was maintenance related ano not prepared to deal with it.
I have helped swap a BUNCH of axle shafts and the folks I wheel with are prepared for that and hour of work and going again.
Its stupid stuff that I have seen take all day to deal with. Stuff like bad rotor buttons that are 5 years old. Rusted out battery trays collapsing and letting the battery short out or go through the radiator. Alternators, Bad battery cables, blown hoses, Water pumps, boiled brakes. Seized wheel bearings etc. All stuff that if it were my truck I would have replaced and wouldn't happen because I do the regular maintenance.
I would start with tune up, new hoses, flush the brake system and as old as your truck is I would concider new brake hoses. Flush the coolant and if you don't know the age of the water pump then replace it.
Most people do not realize Coolant and brake fluid are suppose to be changed every couple of years. Old coolant looses its lubrication properties and its ability to stop corrosion. This can lean to nasty corrosion of the inside of the engine and sized water pumps.
Brake fluid will absorb moisture from the air. As this happens the boiling point lowers and the fluid becomes acidic eating the seals and rusting the hard lines from the inside. 2 years it is time to think of doing a flush.
Lack of routine maintenance:
The time to check the truck is immediately after the trip not just before the next trip. If you drive through deep water you need to give the chassis a full lube and check diffs, knuckles, wheel bearings, crank case, transmission and case for water contamination. Catching it early is always better (and cheaper) then later.
Water sitting in a wheel bearing will cause it to rust and then disintegrate next time on the road. I had a buddy had a front wheel bearing lock up on the hwy from this. He had not drove the truck in a month and did not know he got water in around the locking hub. Headed to the next ride 70 miles from home it seized at 70mph and about flipped his truck. New seals, repack now. At the very least pull the locking hub to see if any water got in within 24 hours of deep water crossing would be a good idea. Most manufacturers recommend complete disassembly of the hub assembly aft water crossings.
As for the gear:
$150-200 at the local department store like Target or K-Mart will get you a cheap tent, sleeping bag, cooler and stove. Have at it!
Best advice after basic gear is make sure somebody knows where you are going and when to expect you back.
If you change your itinerary then you need to make sure that person knows of the changes. If you can't reach them then you stay put till you can. That simple step lets somebody know that if you don't show up where to go looking for you. People changing plans and nobody expecting them or to hear from them is how people end up dying while stranded.
Steve Faucet is a prime example. If he had let somebody know if the exact area he was headed he might be alive today. Instead they are still trying to find his remains and crash site. This guy was super human in most peoples eyes. Set numerous world flight records and because nobody knew his exact travel plans nobody knows where he is.
http://en.wikipedia.org/wiki/Steve_Fossett
Another is the family that got stranded and the father ended up dying of exposure trying to find help for his wife and kids. Nobody was expecting them so nobody knew they were missing and overdue till they had been stranded for nearly a week.
http://www.cnn.com/2006/US/12/06/missing.family/index.html
Welcome to the forum and look forward to the pictures of your truck.