Model LXI
Were you referring to the model 60 that had been converted to use a power nozzle, and has the aftermarket rear wheels clamped on and a swivel wheel underneath? The automatic control module has been replaced as well.
Just by looking at it, I can tell the rear wheels and front swivel were probably replaced when the automatic control module was replaced. The original would have not had a control knob.
And of course the power nozzle was added after 1961, and the hose is from the late 1960's through mid 1970's.
It's had a hard life. But that one is not a true model 61. Unless you saw another model 61 that I didn't find.