Don’t believe you’ll find what you want with single wheels on it, but you can install single wheels on an axle that had duals.
Also don’t think you’ll find one with exact same spring spacing as your old truck.

Much info about swapping a 14 bolt into an AD truck here.
https://www.stovebolt.com/ubbthread.../14-bolt-axle-swap-info.html#Post1249600


•1951 GMC 250 in the Project Journals
•1948 Chevrolet 6400 - Detroit Diesel 4-53T - Roadranger 10 speed overdrive - 4 wheel disc brakes
•1952 Chevrolet 3800 pickup
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"First, get a clear notion of what you desire to accomplish, and then in all probability you will succeed in doing it..." -Henry Maudslay-