To follow on from NormK, most 4-stroke Victas use a 'short PTO shaft' engine, to match the PowerTorque and earlier 2-stroke engines.
So basically, if the chassis was offered with the PowerTorque engine option, it will have the short PTO engine.
Which will only fit another similar Victa chassis, and won't work with other makes - won't cut low, and the blades may strike the inside.
Looks like the Tornado series is one of these.