Looks like the Wiki needs to be updated (it says 3.55's were only in 2WD's) since 3.55's were also available in the 1st Gen 4x4's for sure. Never saw them in a 2nd Gen 4x4, but I've seen them in at least 3 1st Gen 4x4's. All of them were 2.6L trucks, with a 904 Automatic transmission, and all had the plate on the core support listing a 3.55 gear ratio (only I believe they referred to it as "Axle Type : 3.540". or something like that)

My '84 had 3.55's from the factory. Wish I still had the little metal plate from the core support that listed the gear ratio and such (to provide some evidence), but most of my core support is long gone, along with the tag. Had to remove most of the core support when I converted the truck to Small Block. Still have the axles though, removed them from the truck years ago when I converted to a Solid Front Axle.