According to HP books "How to Rebuild Small Block Mopar Engines" the cast crank 73 340s and some 74-86 318s share the same casting number...only noted difference was that the cast 340 cranks are shot peened. Casting number annotated is 3462387
OP: If you want to use a zero balance flywheel and balancer (if you already have them and don't want to swap) you can try to find a 68-72 steel crank, but there's nothing wrong with the cast crank as long as you're not spinning it to the moon or feeding it ridiculous amounts of nitrous or boost. In case you haven't noticed, even the cast cranks are quite robust.
Regardless, whatever crank you use, just make sure you have the appropriate balancer and flywheel combination...
hi does it have a wide or narrow thin parting line on crank? thin is cast wide is steel.
