84 toyota pu and alarm system

OK. Don't laugh. I want to install an alarm system for my 1984 Toyota PU. Here is why: I only use it to haul stuff to the dump, or recycle my beer cans. It's been sitting on the side of my house 95% of the time. It's been broken in a couple of times, and most recently the catalytic converter was stolen. Enough said. I need to install a cheap alarm system on the truck. As long as someone touches it, it will sing. I don't want to deal with all the insurance hassles if something was stolen from it. Here is my question: What is a good, cheap and reliable alarm system? I don't need anything nothing fancy since the truck doesn't have power locks. I was looking at ScyTek G20 on ebay. I don't know much about this brand. Any brand recommendations? Thanks in advance. Car info: 1984 Toyota pickup.

No alarm will trigger simply by 'touching' the vehicle. If a door is opened, or the vehicle experiences an impact it will trigger. There are also optional sensors you can install but they would also add to the cost. I have installed better than a dozen Scytek pieces that people have brought me over the years. They are not what I consider high quality but I have never had one come back for any reason at all. I prefer DEI stuff, so I would recommend something like the Avital 3100. Just make sure, whichever system you decide on, that the vendor will warranty the unit for you.Installer, IT support, and FFL. I need less hobbies.