Some of the engines go back to the mid sixties. The newest one is the OS Max 30 The oldest is the Max 15 with the steel fins.

They were all just run of thr mill standard fair engines from the latter 60's through the early 70's

The Enya 45 and 60 are pretty nice. They were powerful engines for their day. They have ball bearings.

These bushing engines need 25% oil. The two Enya's don't need so much oil.