how to tell the difference between a stock and stroker crank?

[Oneslowgs-t]

Im currently building a 6 bolt bottom end and bought a crank with the 6bolt block.
The guy told me it was 100mm crank if I remember right then I asked him if its the stock 6bolt crank and he said yah. So I asked a buddy of mine and he said the 100mm crank is a stroker crank.
I'm confused.
Is their any markings on the crank to tell me if its stock or not?

On the end of crank shaft( balancer side) It has a S on one side then a C on the other and 1/10 on the bottom side

Also in the middle of the crank it says VV and 73

 

[RvlutionMtrsprt]

Measure the stroke. Pretty simple way to tell for sure what you have.

 

[serviceguy]

It is as easy as measuring the stroke.