I guess we are talking about an AD. Rear springs are totally different, but there are a lot of 3/4 parts trucks around and bushings is usually all that is needed to fix rear springs. Front springs are interchangeable. Back in those days, the rear axle carried just about all of the weight and therefor heavier springs were not needed on a 3/4 ton. The rear on a 1/2 ton was underslung like passenger springs to ride better. 3/4 ton had overslung springs like a truck and they ride like a truck.
