The Hydamatic was first used in Oldsmobiles, starting in 1938, I think; Pontiac and Cadillac started using them later, but I don't know with any certainty when they started. Buick had the Dynaflow, starting in 1948 or so, but I don't know that for sure, either. Chevrolet began the Powerglide automatic in 1950, and Pontiac used the two-speed Powerglide (1953 and later transmission) for a time in 1953-1954 because of a shortage of Hydramatics. I don't know the number of Pontiacs that used the PG transmission- I never saw one in service, but some after-market transmission gasket sets were listed as applying to 1953-54 Pontiacs with Powerglide transmission. I don't think any of this applies to your original question, though.
If anyone is interested in the Pontiac/Powerglide useage, I may be able to find something more on that.
Harvester
