John; The Packard automatic transmission was called an "Ultramatic" and it was an in house made unit. The early Borg Warner automatics, with the mechanical lockup, were developed jointly with Studebaker so they were hence called the "Studebaker Automatic" in the American manuals. Studebaker used these transmissions between late 1950 and 1956 after which they switched to another Borg Warner automatic, that they called a "Flightomatic". The same transmission was also used in some Ford products which made it cheaper to use then the "Studebaker Automatic" out of straight economy of scale. I have heard rumors that Borg Warner did take the "Studebaker Automatic" to Europe after Studebaker abandoned it but I had no confirmation that Jaguar used them, especially as early as 1953. This is good information to know as early fifties Studebaker owners apparently have a hard time finding parts for these units. As for the transmission in your Jaguar not having a cooler I doubt if that was the reason for the mechanical lockup in those units as Studebaker promoted this feature for the fuel economy aspect. I know that the Chrysler Powerflytes often did not come with a cooler either depending apon the car in which they were installed. I case in point is my freind's 1955 DeSotos; one is a Firedome and does not have the cooler, the other is a a Fireflight and it does have a cooler even though they both have the same transmission. Since the Fireflight has power steering and the Firedome doesn't, perhaps the cooler was an option on the cheaper cars. I am sure that as you move down the price scale to a Dodge or Plymouth you would find the same thing, but definatelly not in an Imperial. Best Regards Arran Foster 1954 Imperial Newport Needing A Left Side Taillight Bezel and other trim parts. P.S The technical term for a Gyromatic, Prestomatic, etc, is an M6 semi automatic, at least according to my manual.