I can't find any other pictures of mine and the actual part is tucked into the garage somewhere too far to retrieve. But, it is almost identical to this one.
The Spider Pulling Machine | Compact and Portable

Only difference is mine is not adjustable, I just made it the length of the cab. I made mine out of 2" square tube for the beam and 1 1/2" flat bar for the part that connects to the hoist that I welded to the beam. Drilled holes in the flat bar for the bolt that holds it to the hoist. Use a piece of angle iron on each end to keep the cab from slipping off and your done. They sell it for $160 plus shipping. Anyone with a welder could make it for 5-10 bucks I am sure.

Here is another link to a DIY adjustable one, I hate to link a Chevy Forum on here but here ya go.
cab lift adapter for engine hoist - The 1947 - Present Chevrolet & GMC Truck Message Board Network