can an a new controller control the servos i already have in a plane?

by controller....do you mean receiver?
if yes...than sure...

if you are changing transmitters...than sure..as long as you stay on the same channel and they are compatible

I used some 15 year old servos in my new radios ... works fine!

Yep, I have some 15+ yr old servos that are still flying. (JR NES-505's).

The one to watch out for is old Airtronics. Their old connector had the wires in a different order from everyone else. You can get adapter cords, or just re-wire the connector yourself, then they work just fine.

The signal standard between the RX and the servo hasn't changed at all in many years.

I don't know when things changed, but my 70's servos would not work with my new gear.

Smed - you are ancient!!!

I have used Kraft servos with late Futaba gear. However the technology has advanced over the 70’s products. The component count has been reduced. Surface mounting technology is probably 1000 X more reliable. Price is in the $10 range.

I had some old servos given to me. I replaced the ends and installed them in a plane. They work but are very slow compared to the new ones. They work ok but I wouldn't want to try them in my faster planes. [&o]

As long as the old servos are three wire leads, and you get the wires connected properly, there should be no proplems. If the servos are older 4, 5 or 6 wire servos, the only way they could be made to work on a newer reciever would be to replace the electronics internally. Cheaper, quicker and more reliable to just get new servos.

Futaba G series will work with the j reciever with a splicer type connector. Hobby Lobby was a source of these..

That really sums it up pretty well. These days, $10 gets you a really nice, reliable, servo with pretty good speed and resolution. Compared to what was available years ago, it's down right amazing. I understand if you can't afford $30 on three new servos (use the old ones on throttle, no harm there), but if you can afford newer servos, it's worth it.