Mini trucks use 7/16x20 (I know everything on a toyota is supposed to be metric) bolts on the seat belts. The holes in the roll bar of my first gen 4runner are 7/16x20. A 60s belts bolts are probably the same.
You need IFS wheel hubs, SA locking hubs and rotors. I pretty sure 80 hubs have the wheel mounting surface somewhere in between SA and IFS hubs. So this wont net as much width on an 80 axle as it would on a mini or earlier FJ axle. I have never worked on an 80 so I'm not sure.
If you need...
I have never been impressed with 1st gen 4runner seats. All the 4runner I have owned had a metal bar that hit your lower back. I place a rolled up t-shirt in between the bottom and back of the seat so my back won’t hit the bar. The seats in my 60 are definitely more comfortable.
My old 4runner used to do the same thing due to slop between the splines on the drive shaft. I never really had any vibration issues from it either. Just one other thing to look into.
I have been looking into picking a diesel up for Canada. If the truck is 25 years old its easy to import. Lots of good importing threads in the diesel section. I think the easiest/most cost effective way is to buy a rusted out diesel in Canada then swap everything over to a clean FJ...
Washers will get the job done. A trimmed stock plate is better but mine had rust bubbles on the sealing surface. Make sure you use some silicon to seal the gap.
You can down load the FSM for an 85 pickup/4runner here http://www.ncttora.com/fsm/index.html
The knuckles are the same as fj60s.
Get marlins heavy duty inner axle seal. The other after markets inner axle seals ended up leaking 6 months later.
The same thing happened to me. I used stock Toyota bushings from an 86 4runner and put some locktite on the bolt. Nothing special about the 4runner bushings, it’s just what I had.