Quick and dirty.
3FE trucks (91-92): Iron block, iron head, if the oil is changed and it is reasonably maintained it should go a half million miles with little trouble. If it sounds as bad as you say, probably walk away, or adjust price accordingly to cover an engine overhaul. Transmissions can be finicky, a fluid change on a high mileage unit that has never been serviced is almost a guaranteed trip to the transmission shop. They are all hydraulic. They will be semi-float rears and will be non-abs and have no airbags. Generally will have cloth seats. Pretty much every body panel and most interior trim pieces can be swapped from later models.
1FZ/A440 (93-94): Body and interior stayed almost exactly the same. New drivetrain iron block, aluminum head. Know for head gasket going, but mileage varies. There is a heater hose at the back of the block that is a know problem and is often replaced almost like a maintenance item. Transmissions were better, but still all hydraulic. The rear ends transitioned to a full float design and the truck got ABS. This necessitated a slightly longer birfield up front to account for the reluctor ring. Aside from PHH and head gasket, solid trucks. These can be found on occasion with a SF rear as they were kind of transition years. These would be the earliest years you would find the factory lockers. The fender flares changed a little in this generation and up.
1FZ/A343 (95-97): body remained the same except for the grill lost the "TOYOTA" logo and got the sombrero. Interior got a differnt dash with more buttons and these were mostly leather interiors. Same 1FZ, iron block with aluminum head, same known head gasket issue. same PHH situation. These were all FF rear, had abs and were also available factory locked. The transmissions were an electronic over hydraulic unit and the computers were all OBDII. They would have had drivers and passenger side airbags, but nothing on the sides. 96 and 97 also saw the introduction of the LX450 to the stable which was essentially an 80 with more bells and whistles. They share most all other major components.
91-97 share suspension components, aside from driveshafts. The 91-94 are similar and the 95-97 are the same. That had to do with the A4xx to the A3xx changes in the transmissions. Lastly, if it has a sunroof, it has likely leaked at some point. Check the drains front and rear on whatever you buy to make sure they are connected, clear and draining properly.
As a whole you can't go wrong if you find a good one of any year. Know that the 91-92 models due to them getting the motor and trans carryover will have more parts that have been disco'd, but unfortunately we are talking about a series where the newest truck is now 19 years old, so model specific parts are getting fewer and fewer every day.
Whatever you choose, know going in that owning an 80 is an investment. Nothing for them is cheap. You have to remember, particularly with the entry of the 80 series, the LC became the flagship for Toyota in North America. They were not mass imported like the mini-trucks or mass produced like the jeeps of today. They are almost a niche market and as such the aftermarket, while growing, is relatively limited and as such pricey in our world.
Whatever you decide, plan another $500-$750 for maintenance items. Knuckle rebuild, belts, hoses, plugs, wires, brakes, etc. to ensure you have a good solid runner.
Prices for 80s on CL and the like have gone S T U P I D. I have seen good 96 and 97 units sell for north of $10k, insane in my world, but good rigs can be had, but you will want to budget around $5k to get one that isn't a pile these days.
Sorry I got long, but perhaps this will help give you a little idea of what you will be looking for/ at when you go.
-Matthew