Welcome to the forum.

Your machine is a 924 series commonly referred to as a "twin stick"
It most likely is a 1979 model.
The model and serial # tag should be located on the tractor body.
Probably model # 924044

These are well built snow blowers and are considered by many to be one of the best series of snow blower Ariens has produced over the years.
Your machine looks to be complete and in pretty good condition for it's age.
Should clean up pretty well.

This is a good website to learn more about these machines:

The Ariens 1960's and 1970's Sno-Thro info site.

Owners and repair manual for similar 924 series machines:

 

Is that missing a chute handle crank? Or is that how they came?

 

Pretty sure the chute crank rod routing has been modified.
I would think the rod should run under the heater box, maybe someone more familiar with these 10HP late series machines will chime in:

 

The bucket shape indicates it's a later model twin stick. I have an early model twin stick with the tear drop (sides) bucket. Your machine also has a newer design auger gearbox.