Those are MKS HV69 servos. Back in the day mainly the radio manufactures made servos, today we have a few companies that just make servos. The MKS are my preferred brand at the moment although completely overkill for this airplane. The HV69 is a wide voltage servo that will operate on 5V to 8V, has metal gears, ball bearing output shaft and 149oz of torque at 7.4V.

From a beginner standpoint the S-148 servos are a great choice and will fly your Kadet just fine. As you progress you may gravitate to a specific type of aircraft, perhaps warbirds, giant scale aerobatics, pattern. Or you may just stick with vintage sport airplanes. Point is specialty airplanes require specific servo performance and at that point you will know what to look for.

I have to give kudos to Hydro, I didn’t think of the narrow band change in 1991, I’m glad he did and your radio has the correct specifications.