Engine Cradle - Heavy Duty - 1 in Square Tube - Hardware Included - Steel - Black Powder Coat - Each. Heavy Duty with provisions for mounting wheels and are made of 1" square tubing with black powder coating. All cradles are for V-8 engines, include Grade 5 fasteners and may be easily disassembled for storage. Standard Duty cradles accept wheel kits with 3/8" studs. Heavy Duty cradles accept wheel kits with 1/2" studs. Wheel kits sold separately.