If I had the choice I'd have 416. If I'm not mistaken 4 speed doesnt have cascade. No cascade means no true 1000rpm which most decent Chippers need. There is another way to get it but its difficult doing. Shafts for 406 are 'common' I'm getting front pto off Ac price this month as for a 416

with reguards to reverse speed the 6 speed reverse is quick enough (almost car speed)