</font><font color="blue" class="small">( Just remember that with any QH you are changing the one standard that no one has talked about: the PTO-to-3-pt. relationship. Yes, there is a standard to that, too. Most tractors are fine, but a lot of Kubotas & a couple of the NH tractors are beyond the limit from factory. Why?? )</font>
Never heard of such a standard, so it would be great if you could quote your source.
There have to be at least a half dozen PTO shaft lengths in every farm store I've shopped in. Plus different spline diameters, tooth count, clutch design, et cetera. It's also why new PTO driven implements usually come WITH their own PTO drive shaft. There IS no such thing as "one size fits all".
As far as length goes, when buying a replacement I select the one most closely matching the minimum distance between the tractor PTO spline and the implement transmission spline. Longer than that, and you'll bend/break/crush something during TPH travel. Any fine tuning is accomplished with a hack saw. I've gotten lazy, and have cut down recent shafts with a reciprocating saw. A band saw would be best, but they're harder to justify in the budget.
Anyway. Quick Connect devices necessarily lengthen the distance from the PTO spline to the end of the lift arms. That distance is equal to the additional length you'll need on the PTO shaft to compensate.
//greg//