A while back I found myself in a situation where I needed to pick up some heavier items to put into my pickup truck and ended up using an engine hoist. After packing the engine hoist into the truck one day I thought it would be a good idea to find a service crane for the truck. I ran into two issues...
1) Service cranes were pricier than what I wanted to pay
2) My service truck bed wasn't designed to carry a crane.
My answer was to just build something myself that would solve these issues. We copied the basic design of an older cable crane and used cheap wenches to power it. Its not completely done, but very close, I will update this post as we progress.