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). Of course, it takes a four barrel intake and a conventional distributor but a refresh on the engine and regrind on the hydraulic roller from Oregon Cam grinders (or even a factory 360 LA hydraulic roller or the right factory 318 Hydraulic roller makes a truck engine that you have to experience to believe. Not on all out mid range or top end performance, but on low end torque. Driveline wringing diesel kind of grunt torque.