PTO/Clutch Repacement

Have a 2009 CD, LT1045, Model 13RX11CH056 with 550 hours and just replaced the clutch. Two questions, (1) is that a normal
clutch life for OE? and (2) at what speed should you engage the PTO (low, medium, high)? Thanks.

Yeah, that's in the normal range for a PTO clutch, depending on operating conditions, although it's possible to get many more hours out of them. Tough mowing conditions and frequent restarts of the blades will shorten the clutch life.

Engage at full throttle for your unit per manufacturer's recommendations. Recommendations will vary depending on the individual machine. I try to disengage mine at low rpms whenever possible.