My old hi tin 443 head was a 1977 model did the triple gear update and JD knife roll conversion through whole goods in 1998. Been trouble free in all that time also have done chains sprockets, deck plates, tensioners etc.

Bought this 693 head used from a dealer and was led to believe it was late enough to have factory updated gears and knife rolls on it. (My mistake for trusting anyone's word and not asking for further proof documentation)

In going through it I've found some issues that were not as advertised.

Had an upper gathering chain sprocket shaft with bearing and bushing out, found quite a few broken bolts holding the the front snapping roll housings on. Couple have been helicoiled previously and one gear box is cracked. Once apart is when I verified the gears were not updated as previously thought. Appears it may have not been original factory knife rolls but was upgraded to knife rolls but the triple gears had not been. 

Little disappointed so far but it's solid enough to build back the way I want it to be and will know it's been done right and up to "MY" standards and not someone else's.