AHM was selling Rivarossi built engines for years, I’ve seen ads in MR from1969, and probably before…they were extremely common. All mine are the older versions.
They stopped , and then I saw them offered again in MR, I believe as Rivarossi. I’m thinking around the '90’s, or early 2000’s. I don’t know when they switched to can motors, but my guess would be most you see offered today are the older ones, since AHM had flooded the market with them back in the day…
It may be difficult to find another of the newer production. But not impossible…
Paul