79-80 = 4.37
81 =3.90
82-90ish (5spd, 4cyl) =4.10
80's-94 4 banger, auto =4.30
89-94 V6, 5spd or auto, big tire pkg (31's) =4.56
there were some (very few) trucks/runners in the late 80's that had factory 4.87, but I'm not sure what pkgs they came with.
88-later, V6, and turbo trucks all use the V6 carrier, gears and lockers aren't interchangable with the 4cyl version. You can swap the whole 3rd member though.
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"I find no fun in being nutsack deep in stank decomposing swamp in order to extract some inbred idiot with a S-10 blazer welded on a ford f-250 frame cause he has open diffs"
- usmcdoc14