This one is of the front of the dolly. It looks like the casters are attached to the 3/4" plywood, but they're part of a steel frame engine dolly. You could probably just as easily make a dolly out of 1" plywood and 4 casters. I had to taper the front so that it would fit between the outriggers of the engine hoist. Obviously needed the engine hoist to get the engine mounted on the k-frame in the first place. The k-frame has a small skid plate on it, so it won't rest level on the plywood without the 2x4s underneath. Didn't matter, though, as I needed the extra height anyway, so that the control arms, tie rods,and lower ball joints would sit above the engine hoist outriggers also.