My understanding is Packard designed and built it's own axles up through 1955.
https://www.macsmotorcitygarage.com/1926-packard-pioneers-the-hypoid-final-drive/ In 1956 Packard introduced the new limited-slip "Twin Traction" differentials. Presumably as a cost-saving measure, all the axles, limited-slip or not, were manufactured by Dana, though the technology it seems was developed by Packard, the patent is 2769353 "DIFFERENTIAL GEARING" - Edward L. Nash, assigned to Studebaker-Packard Corporation, documented in SAE paper 560247 "The Packard non-spinning differential" by Forest McFarland and E.L. Nash.
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