You are correct about the 122″ Packard team at Indy in 1923.
But there was no connection between the Packard Cable Specials and the Packard Motor Car Co.
The Packard Electric Company was founded in 1890 by the same Packard brothers who built the car by that name in 1899. In 1903 the former was sold to the General Electric Co.
From 1919 to 1932, when it became a Division of the General Motors Corp., the Packard Electric Co. was an independent company.
Leon Duray, who with Ralph Hepburn took the two Packard Cable Specials (front-wheel drives) to Europe in 1929 obtained sponsorship from both Packard Electric and E. L. Cord. Although the Cord name was not publicised it was E. L. Cord’s intent to forward the cause of his new FWD L29 Cord by the Packard Cable Special successes in Europe . . . which did not meet expectations, to say the least.
The information on the Packard Co is from The Turning Wheel”, by Arthur Pound, 1934. It is the history of General Motors upon their 25th Anniversary in 1933. Doubleday, Doran & Co, New York.