Big Block Crankshaft Question

[z28luvr01]

Last month I picked up a crankshaft for the Corvette. It was advertised as a NOS 396/427 crank and has the correct casting numbers. Late last night, I get an email from someone who bought a crank from the same guy. His had the 396/427 casting number, but had the physical characteristics of a 454 crank (a 4" stroke vs/ a 3.76" stroke, and a dowel pin at the flywheel end). I open my box and, sure enough, same thing. Naturally I'm upset about buying something that's not as advertised, but I'm more concerned with making sure I can still use the 427 balancer and flywheel. The 396/427 crank is internally balanced while the 454 is internally balanced.

With all the backgroung out of the way, is there any way to tell by looking at the crank to tell how it's balanced. If it's internally balanced, I'll just suck it up and get the right balancer and flywheel since the 427 and 454 bores are the same, but if it's externally balanced I'm ready to make a federal case about it. I'll provide pics if needed. TIA.

[Camino LS6]

Last month I picked up a crankshaft for the Corvette. It was advertised as a NOS 396/427 crank and has the correct casting numbers. Late last night, I get an email from someone who bought a crank from the same guy. His had the 396/427 casting number, but had the physical characteristics of a 454 crank (a 4" stroke vs/ a 3.76" stroke, and a dowel pin at the flywheel end). I open my box and, sure enough, same thing. Naturally I'm upset about buying something that's not as advertised, but I'm more concerned with making sure I can still use the 427 balancer and flywheel. The 396/427 crank is internally balanced while the 454 is internally balanced.

With all the backgroung out of the way, is there any way to tell by looking at the crank to tell how it's balanced. If it's internally balanced, I'll just suck it up and get the right balancer and flywheel since the 427 and 454 bores are the same, but if it's externally balanced I'm ready to make a federal case about it. I'll provide pics if needed. TIA.

Look at the counterweights: Are they drilled? Internally-balanced versions should have large diameter holes drilled into the counterweights - empty to lighten them and lead filled to make them heavier. The casting numbers could be the same, but I doubt it. It could be a service part issue (one size fits all) that GM used to save money making replacement parts- they do this all the time. I'm sure that there are other ways to check as well.

[76ChevyTrucker]

what Camino said, and as far as I know, at least part number wise, the cranks are different (already had someone try to do this), so I dunno if it'll work or not.

[z28luvr01]

Thanks guys. I just got an email from the seller telling me it was internally balanced. I will check tonight though, because he already lied to me once.

[balthazar]

I am interested to learn how this turns out. Not familiar enough with Chevy at the parts-number level, but I can tell you that PMD changed casting numbers where you would be hard-pressed to tell what the differences were. I would HIGHLY doubt Chevy used the same casting number for 2 differently-balanced cranks.... in fact I would say it's IMpossible, but again; I don't deal with Chevys on a parts-number level. But Pontiac & Buick did not do that sort of thing.