Ace is in fact a Thunder Tiger brand that is either no longer around or is just not around in North America. If it is an Ace servo, the parts from the AE ones will not fit. They were changed just enough even though it is the same servo. They had some running changes with them.

They are a very durable and reliable servo. I had mine for 3 seasons of buggy and truggy, then a year in a rock crawler. I finally killed it by submarining it in a trail truck.

I would have no problems getting another 1015 at all.

BTW, it's a Futaba spline on the Ace/AE servo's. They were never made by Airtronics.