I say keep the old truck, but that is coming from another guy with an old truck. I couldn’t get much for it, but it’s easy to maintain, I do almost all my own work, and even many major repairs would still be cheaper than a decent used car. It has over 200,000 miles on it, but many of them make it over 500,000. It’s best to shit, but I don’t have to worry about it. I park and drive wherever I need to, throw whatever I need into it, and let the rain wash it when it happens.
Personally, I love the stigma that comes with a beater vehicle. It may look terrible, but it will run far longer than most people will have their cars and I know more about it to keep it functional than most people care to learn about vehicles. It’s all manual parts and crank knobs, so nothing is prone to failure that can’t be rigged with the tools I keep inside of it. I park it wherever I want without worry of dings or theft. I take pride in the fact that it costs less per year to maintain than most people pay for one payment. It’s no hybrid, but as far as old cars go it is a stick shift and rwd, so it does just enough with nothing extra. Hanging onto it and forgoing other cars has been one of the most frugal choices I have made.