All of the older Toyota trucks were very good and quite reliable. My first Toyota was a 1981 Hilux 2WD truck with the 22R 4 cyl engine and it was a great truck, I put over 200K miles on it before I traded it for a brand new 1988 Toyota extra cab 4x4 also with the 22R 4 cyl. My 88 Toyota 4x4 had almost 300K miles when I finally retired it in the fall 2004 when I bought my current 05 Tundra AC TRD 4x4. The friend I sold my 88 4x4 to is still driving it and recently did some body work and repaint and it looks like new again and still runs great. The 4 cyl 22R engines are very reliable but in my experience are also prone to headgasket failure. I had to do the headgaskets on BOTH my 81 and my 88 trucks. Other than that they were pretty much bulletproof and the headgaskets BTW didn't need replacing until the trucks had many miles on them. One thing though is for a small truck with a 4 cyl engine I was not really impressed with the mileage. The 81 2WD was actually pretty good but the 88 4x4 was not that great, unless I drove it at 55 MPH it had trouble getting any better than 20 MPG. Actually when it was working a little like if I was pulling my small boat or fighting a head wind it only got about 15 or 16 MPG, same as my Tundra gets under the same conditions and the Tundra is much bigger with A LOT more power.
They were all good trucks but if you are looking to get an older one to mod for off roading the 1985 and older solid front axle trucks would be a good choice as lift mods are simpler and cheaper to do.