1. Sorry to hear about your fathers passing.
2 DO NOT SCRAP that truck, it looks to be in very good shape and that it is not heard very often with a LUV, sounds like it should be an easy fix with the help of the experts here (I am not one of them
). Personally, I would fix it in your fathers memory and keep it if possible. I am rebuilding my Grandfathers 39 Chevy and will be putting probably 4 times of what it is worth into it to get it back to running/showroom condition in his memory. Sounds you will have to spend very little to get that truck running again. Not sure what type of mechanic you took it to, but todays cars tell you what is wrong with them and computers tell the mechanic how to fix them. The LUV was built in the pre-computer era and newer mechanics have no clue how to fix or troubleshoot older vehicles (just like auto parts stores now cant do anything without the computer anymore). If these guys here cant get you on the right track, you need to find an old school mechanic in your area who can actually figure out what is wrong.
Good luck!