3/8" thick stainless? If they are 8 gallon and 3/8" wall thickness, I would doubt they are milk cans at all. But they do look like milk cans. Certainly not standard milk cans. That would be pressure vessel specs. Hope they work out for you.
Damn, 3/8 is gonna be heavy.
Overhead the albatross
Hangs motionless upon the air
And deep beneath the rolling waves
In labyrinths of coral caves
An echo of a distant time
Comes willowing across the sand
And everything is green and submarine