Ok, so we know that round one was a miserable failure.
Round two:
Dash back out of the truck, in the house, stripped down and all over the kitchen table again. (Can you tell that my wife is not home this weekend?)
Sat for 3.5 hours yesterday re-pinning the plugs for the cluster. Pretty sure I am missing one or two little things there are I have one hot wire and two grounds left over. Also, the high-beam indicator is always on with the headlights on. Not sure about that.
I do have dash illumination, tach, and CEL though. Speedo will work correctly, obviously, since it is cable driven. Headlights work, have not done wipers or turn signals yet though.
Ignition switch plugged right in, seems to work right. Headlights were easy because the main light switch is the same from 86 (maybe earlier) through the mid 90s. Just have to re-pin the high/low dimmer, which is easy since I am going to floor-switch.
The climate head used the same colors and wire ends, just had to transfer them from one hard shell to the other. I am a little confused about one thing with the CC head. The 87 plug has 5 cavities. The 89+ has 6. I filled all the spots on the older connector and still have two wires in the newer one.
The two left were for AC, so I cut them off and dead-ended them since I don't have AC.
Radio head unit wiring is all the same, but the plug was cut off the new harness, so I moved it over. Also, the 89+ dash harnesses have no provisions for the dash speakers since the front speakers were moved to the doors. The dash speaker wiring is only 6 wires taped into the main dash harness, so it is easily removed and laid into another one.
I just laid both harnesses out on the dash and taped the speaker wires off where I wanted them.
Fuse block looks different at first glace, but if you look harder it is the same body, it just has some extra pieces clipped on it. Took them off, and swapped the wire retainer...
Tada. 5 minutes work and I have an 87 fuse block in an 89 harness.