Rear Axle Swap

The idea to swap the original rear axle for a newer, more modern style axle, started when we found out that one of the rear brake drums was warped and could not be straightened. After scouring all local junkyards and searching the internet, the only one I could find was $250.00 which was way out of line. Of course, this problem, with lack of availability of parts, would only get worse over time, not better. In addition to this problem the factory gear ratio was a std. 4.10:1 and an optional 4.78:1. Both of these ratios are very low and greatly reduced the top speed of the truck, as well as the life of the drivetrain.
After taking some measurements it was decided what axle to buy. A full size Chevy 1/2 ton pickup from the mid to late 1970's used a GM Corporate 12-Bolt rear axle which had the same 5 on 5" bolt pattern as our 1953 Dodge 3/4 ton Truck. Also, parts are available on the shelf at any auto parts store for these axles and brakes which were used in hundreds of thousands of trucks in the 1970's and early 1980's.
The 12-bolt axle that we used had the extremely high 3.08:1 gear ratio and came with perfectly good brake drums that only required turning. After checking the axle to make sure the differential was in good shape and there were no major leaks, the pinion seal was replaced and the leaf spring perches and shock mounts were cut off and re-welded to the correct locations. At this point the axle bolted right up to the factory Dodge leaf springs under the truck. When it came time to connect the driveshaft to the differential pinion yoke it was discovered that absolutely NO modifications were necessary. Both the 1979 Chevy axle and the 1953 Dodge driveshaft used the same size u-joint. Go figure. In addition, the length of the driveshaft also worked, as is, with the new axle. Sometimes things just go your way.

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