Anybody remember 5 wire servos. Or servos the had their electronics integrated in the receiver. Those servos cost abot 1/4 of other brands. Then there was Heathkit and Kraft and Proline and who knows how many others.
We're pretty lucky these days. For the most part we have but two types to worry about--Futaba and so called universal. With about a minute of effort there is only one type.
Life is much simpler today.
BTW that type S29 servo is about 25 years old. I still have some S28's that are still very serviceable.