[Mr70]

You can see a picture of it n Action on Page 56 of Micheal Antonicks,"Illustrated Camaro Buyers Guide".
It was a very rare option in 1969,RPO V75 available for All Chevrolet cars,and Cost $23.20.
It was scheduled to be an RPO for the 1970 Chevelle,but was Cancelled early,before production.It was available over the Parts Counter as well.
Vacuum Operated Trunk Mounted Cylinders were installed behind one,or both rear tires in the trunk wheel hose.You inserted a can of Liquid tire Chain,and screwed the Vacuum operated Plunger top onto it.The Button was mounted on the dash,and worked of Engine Vacuum,through rubber hoses.Once depressed,the Plunger in the Trunk applicator would engage and the Aerosol can would spray onto the tires tread.I believe it was basically Ether,to melt the sorrounding Snow.
It was most installed on cars headed for the Ice belt states,as compared to the sunbelt obviously.
I have the exact same thing Camarojoe is showing,as well as a Cardboard Parts counter display,with Easel & Banner,and I found an NOS Dual Liquid Tire Chain Deluxe Acc.kit that they would sell over the Parts counter,to install in a car seperately.
1969 Cars built with RPO V75 from the Assembly line:
Camaro-188
Chevelle-278
Impala-2086
It was cancelled for cars built off the line in 1970.