The JD850/950 are Yanmar tractors just in JD green. The twin identical sibling is the YM2500. The YM2610 is a twin, just not fully identical. The YM2610 has the power-shift.
The YM tractors have the international PTO that is a 4-speed. JD for the NA market is only 540rpm.
PTO selection Speeds are as follows:
These are at 2200 + engine rpm.
If you ever decide on buying a Japan gray tractor, get one that is a clone of a JD. This way, parts are easy to come by and find.