for 14 years I drove my old classic 73 celica...poor old car had 334k miles on her (not the engine...that only had 215k...lol) and I made a few very long trips in her, the longest being almost 1800 miles from Albuquerque through Tucson to Corvallis Oregon. On those trips I aways did the following:
Pack a "box o' Chemicals" to include oil, water, brake fluid, Pb Blaster, windex, wheel bearing grease, starter fluid (car was carb'd) and Rain-x.
Pack a "box o' parts" to include a spare fan belt, a small length of heater hose, some vacuum hose, hose clamps, spare fuses, various sized nuts/bolts/screws, some lengths of wire of different gauges, crimps and connectors, a roll of electrical tape, a roll of duct tape, an empty (yes, I prefer this item to be empty) gas can, a wire coat hanger and some shop towels.
I also took my service manual, my road trip set of tools (small plastic toolbox with the basics plus a few extras), an atlas, a couple flares, both my maglights, and a first aid kit. If I was travelling during winter I also packed tire chains, gloves, a blanket, and a small folding shovel.
Always check the air pressure in your spare before setting off and make sure you have at least the stock jack. Also if your running special wheels, make sure you have the right lug nuts for your spare if they are different.
A cell phone is almost a must have, but here is a little trick some people dont know. If you dont have a cell service buy a used cell phone and keep the battery charged for your trip, even without a service plan you can still dial 911.
With a 33 year old car you would probably NOT be surprised to know that I have needed each and every item I listed at least once. On one trip I was between Barstow and Needles and blew a heater core hose inside the car! after my intitial shock and near panic stop from the hot water spraying all over the car including my leg, and steamin up the windshield, I was able to pull out my "box o' goodies" and fix my car right there on the side of the road, and was running again in less than a half hour. Driving around in that old car made me feel like MacGyver!