Need a steel 318 Crank. Where to buy?

Good luck, very difficult to find! Try 318-equipped trucks/vans from the late '60's-early '70's. As you likely know, the majority of 318s came with a cast crank, I don't think any cars had them since they are generally not a hi-performance engine. I think the truck crank has a '318-3' # on it somewhere, maybe someone can corroborate.