Try reasoning with your parents a bit
1) they are concerned that you will screw up the red truck. Explain to them that it isn't running correctly right now, and its just going to sit there and rot unless you do something with it. You've learned a lot from working on the runner, and you're comfortable doing another engine swap. You've learned how not to drive 9thanks to your brother)
2)right now they have 2 pretty much worthless vehicles sitting in front of their house (yes, I know you can part them out, get some money, whatever. A vehicle with a shot motor and a rolled vehicle are considered pretty much worthless to most people) By just letting them sit there, they're gonna deteriorate more, and be worth less.
Also, if you do fix the red truck, there's nothing wrong with keeping the 3.0 It isn't a bad motor. Its had some issues, on the whole, but so have many others.
