It's hard for some to grasp that type A in it's original form, has not been available since the prohibition of the use of whale oil in the US. The original Type A worked just fine but it is just flat not available in it's original form. There is no law that disallows folks from putting any red tinted oil on a can and calling it type A but it ain't going to be like it was in 1951. The funny thing is that type A wasn't red yet. It looked just like any other low viscosity oil.
The throttle valve rod, or TV rod for short, controls all functions other than gear selection and it's all done by pressure with a governor for speed sense. The more modern Ford AOD transmission works the same way but it uses a cable instead of a rod. It wasn't till early in the 60s when they started using a vacuum modulator valve.
This Wiki has a fairly good account of Ford transmission fluid changes but it's not totally correct or complete.
https://en.wikipedia.org/wiki/MERCON