Did not mean to imply you were abusing your head.

Just wondering how the drive torque compares from a later 00 series vs older 20 series.

I run pretty much the same scenario of conditions as you although a little slower on ground speed.

I agree one piece billet would be ideal and there is probably a market for them if some one makes them.

I converted a 443 to updated gears/knife rolls in 98, ran 1 year on 4420 before switching to 6620. I ran it until I got the 693 in 2013. Had no issues with updated gears in that time frame.

1 gearbox of the 693 was replaced due to a fracture in the housing where the top drive sprocket exits. That is when I identified these were not the updated gears. The other 5 rows are still running with the older gears but I am mindful of that potential weak point and try to not crowd or abuse things.

I have seen others mention of running a 6 row on a 9600 and having to run pretty fast ground speeds to keep the machine full. I would guess that would be running at or beyond the design specs of what the early 643 were designed to handle.

I agree these are quite durable heads and probably many out there running way beyond what was originally considered the usable lifetime. Also agree see no need to upgrade to more expensive unit.