What are the dimensions of the wood box you built? Looks nice.
The 3/4" base is 48" x 33" so it would rest on the forward tube of the rack. I've included afew images, to confuse things.
I angled the forward corners of the base to fit between the roll cage.
I notched the top front of the box to avoid rubbing on the roll cage.
The box is 48" x 32"; abit smaller than the base, because the roll cage is sloped back alittle. The sides are made of 1/2" plywood and are 6 3/4" tall. The box extends past the rear bumper by an inch or so. I'd make it 31" deep next time.
The chain saw is securely bungied in. Bungies are hooked into three eye-bolts.
I used construction grade plywood left over from our house build. It was free. I keep the Dirt Pig in the garage so the wood will last for years.
Al