I have two flywheels, both came off 9N's but they are different in that one weighs about 50 pounds, the other about 30 pounds. The 50lb unit came off a 39 that I had as a parts tractor, it had an 8N short block with 9N parts. The 30lb unit was mounted in my s/n 9N292 engine which had been sort of rebuilt. It has a new ring gear and is tapered around the outer diameter about two inches which causes it to be lighter in weight. Wondering if and when the lighter unit was used on 9 or 8N tractors or perhaps was a V8 unit and got a tractor ring gear installed. The new ring gear makes it attractive to use in my rebuild of the s/n 292 engine, but would like to know more.