Are you sure that isn't 3.23 gears (or probably 3.21 in an 8-1/4 or 9-1/4 axle) with the overdrive? Sure, chrysler made some offset pinion 8.25 rear axles with anywhere from 2.45 to 2.18:1 gears, but I've only seen overdrive transmissions (automatic or manual) used in 3.55, 3.90, or 4.10 gears in trucks. In all honesty, I would be inclined to look for a 5.2 magnum NV 3500 (Dakota) or 4500 setup (Ram).