Angle steel to strap the top inside of the cabinet.
https://www.menards.com/main/hardware/sheet-metal-rods/hillman-reg-steel-angle/11713/p-1444432402715-c-9215.htm
20” Low Profile S Gusset Floating Shelf Supports for under feet. Only have 8” of clearance to bottom of cabinet so cannot pick a...
I scored great prices at HD on 20 gauge Husky Heavy Duty extra wide cabinets (60% off). My plan is to mount 4 42” lockers on the back of the garage to hold the kids toys and things. Then two 5 or 7 drawer lower cabinets in a separate spot to the side to hold my tools.
The Husky directions...