In case anyone asks about shulker boxes, the reason this is a recalc is because they were labeled as pocket dimensions, and the feat was rejected. Without Shulker boxes Steve can lift 37 stacks of 64 golden apples. Golden apple = 8 gold blocks and an apple. 1 block = 1,000,000 cubic cm. 1 cubic cm = 19.3 grams, so a block weighs 19,300 kg. There are 8, so 154,400 kg. An apple is 0.1 kg so 154,400.1 kg. 64 of these would be 9,881,606.4 kg. 37 of these stacks weighs in at 365,619,436.8 kg (Class M). An Iron Golem can throw steve holding all of this 3 blocks in 0.5 seconds. so (365,619,436.8/2) x (6 x 6) = 6,581,149,862 joules = 1.5729325675 tons of tnt (Building level)
Just a recap
Lifting strength:365,619,436.8 kg (Class M)
Durability:1.5729325675 tons of tnt (Building level)