I was having similar issues on The Whale recently. I did similar things as you...
Replaced starter with new and used one - all testing good (even did gear-reduction vs. regular)
Replaced dual battery setup with new Optima red-tops
Replaced battery connectors
Replaced on fender...
I've got a strange issue that I'm wondering if anyone can provide info on.
I've got a 350 in the 91 FZJ80 and it continuously burns up the plug wire closest to the firewall on the driver side. Let me clarify...it is burning it up at the connect to the plug from the inside. It isn't fouling...
http://www.tekonsha.com/tevoyagerintro.html
They have wiring diagrams on thir website....
And yes...it does need to be connected to tell which is hot. Also, once I got mine hooked up, I had to hook up the trailer to the truck in order to test it b/c it uses the trailer for the ground.
I just replaced my radiator on my '91 a month or so back. It is not fun, but there are 2 really good posts on this site that will help you. One of them even gives you a list of tools you need. Do a search on "radiator replacement" in the 80 forums.
The hardest part of it is getting to the...
GBell....
My "D" is out at both the shifter and the dash -- haven't broken into either of them yet....write up the steps when you get the one on the shifter complete!!!
Ok -- so, they pulled J over for the bumper -- measured 22" in front and 27" in rear. They said technically, the 80 is considered a "passenger car" and not a truck, so the bumper regs for Truck on their website don't apply for the 80. They ticketed him for expired DL...warning for bumper...
So, I just bought an '91 80 and will be picking it up next week. I am curious to know what years are compatible with each other -- mainly with respect to body pieces, interior pieces, and drivetrain.
I also understand it will need a new radiator soon -- prefer alum...any good sources...