Looks like the long saga is finally over:
I ordered a new MC from Land Cruiser Parts. It's an AISIN unit and it stated it came with the cap (as mentioned before my cap was very loose). When it arrived the cap was not in the box. I contacted them and they sent it out to me. It has a different connector than the round one on mine but that's an easy wiring fix.
I ordered stainless steel lines from Cruiserparts.
I went ahead since I am on a tight budget with this thing and got some 1993 4Runner front brake calipers from Autozone as well as a set of rear brake shoes.
I kinda bench bled the MC, but since I was replacing brake lines the entire thing was full of air anyway, so I didn't go overboard with it. Just stuck some fluid in there, rigged up some aquarium air hose line into rubber stoppers and pushed on it a bit to prime it more than bench bleed.
I did not remove, nor turn, the rotors. I measured them and they were within spec. They did not have ridges on them. I understand that I -should- have and at next pad change I will probably order new ones, but I rarely drive this except to take the dogs to the woods, or if I need to go to a work site and my wife needs the truck, and I also had to work outside and get this done before the snow flew, which it did, twice, this week.
The calipers went on fine (after I reversed the shoes and cut the dust thing in the back per recommendations in other threads). The brake shoes were oriented in the right direction but they have squeal tabs on them I guess and I had to switch those on the same caliper to get them to fit. The bolt holes would almost line up, and they were clearly clearing the dust thing, but they wouldn't go on. Switched the shoes and they went right on.
I did have to get a 1/4" spacer so my wheels would fit.
I had already rebuilt the rear wheel cylinders earlier trying to chase down the problem and the rubber was good on those so I didn't do anything in the rear other than put on the new brake shoes.
In the category of "pay attention" The brake shoes come wrapped together. The first ones I opened didn't have the stud on them to hang the parts off of that actually operate the brakes, so I banged out one from my old brakes and put it on the new ones. Of course when I opened the other set I saw that they both had the studs in place. Lesson learned - check everything first before making a dumb assumption, but since the shoes are all identical except for this it didn't matter any.
I gravity fed the rear brakes (again, since the lines were replaced and the whole thing was full of air) until clear fluid ran out of both of them. Then I moved to the front and gravity bled those. Then I called my wife to help with the brake pedal as I bled the whole system quickly. Since I had "primed" the MC (but didn't make sure every single bubble was out), and gravity fed the entire thing, the actual "press, hold, release" bleeding at all four corners took only 15 minutes or less, and half of that was trying to get my creeper to move on my tore up driveway.
Got in, went around the block, mushy brakes, remembered to jerk the brake lever a few times, did that, felt them tighten up and now they work great.
Since I went with the 87 MC instead of the larger for the 93 4runner brakes there is slightly more brake travel but they stop great, hold on hills with the E-brake, etc.
Now let's hope I don't get another lock up in a week but I think this entire thing was the fix:
The old front calipers were pretty ruined. The rubber was tore and missing, etc. The pistons looked decent but I didn't blow them all out either, just the fronts that came out easy.
The MC, however, wouldn't return. Once it was removed and I pushed the piston it would sometimes come back, sometimes not. That had to be why my brakes were locking up.
