I can't be of much help with decoding the trim tag, but I believe all Grand Wagoneers of that era (and up until the last in 1991) were pretty much the same.
They all had the 360 v8, 727 automatic 3speed, and I believe all had the 229 T-case. They also all have D44 front and rear axles. I believe limited slip was an option, as well as a tow package which came with a hitch, and lower gearing.
Anyway, I noticed that you plow snow with your wagoneer. I was wandering if you would be willing to take and post a couple pictures of how your snowplow mounts to the front of the wagoneer? I recently acquired an older 7'western plow, and would like to mount it to my 87 grand wagoneer to use to clear my 3/4 mile driveway. The plow did not come with the "truck side" mount, so I need to fabricate something. seeing how yours is mounted would greatly help with my design.
maroon 1987 Grand Wagoneer. stock for now...