Hi Beech,
The three piece rollers were only used on the larger (pre 1950) version of the 20 inch. The 20 inch Atco light had a two piece roller. In the 14 inch Atco light the rollers were two piece up to the mid 1950's and then become one piece. It should be noted that three piece rollers were also used on the larger mowers.
With the flywheel, from memory it is the right hand number. Date would be 3/56.
Kind regards,
Sir Chook
