Was at a friends house , he was organizing his engine cabinet(50 years of flying C/L & R/C). He handed me a ST G21, with very little time on it. He had added a R/c carb at some time. Said he had bought the engine to fly combat(mid 60s) ended up using it on a R/C trainer for a few flights. He also has a ST .15(?) that looks brand new. Might have to see if I can take a picture of it to post.
Steve