Craftsman Sears PTO Mower Deck 842265112

Looking for info on Craftsman 60" mower deck #842265112. This is a three point hitch implement, probably 20-30 years old. Is this a Category 1 (one) or Cat 0 (zero) implement, what is the PTO speed required (540, 1000, or 2000 RPM?). What PTO shaft size on tractor? The Sears Manual 14141 is no longer available. I'm trying to decide if I can use it with a 1951 Harry Ferguson TO20. A 2000 RPM PTO speed on the deck label makes me think it's some proprietary product, not standard. I haven't seen it, trying to decide if it's worth the trip. Any info would be appreciated.