another question on chevy flywheels

Hi again,
On another post I stated tha i'm pulling out a 350 chevy motor and putting in a 400,but I can't use the 350 flywheel on the 400 motor ,so the question is how can i tell just by looking at one a 400 flywheel,over the more common 305/350 wheel.
Thanks russ

 

the 400 is what they call external balanced...the flexplate has an extra balance weight welded on it.

 

I'm not sure if you meant "flexplate" or "flywheel"...but here's a 400 SB flywheel. The back side (that faces the motor) is the most important for distinguishing it as being externally balanced.

This is an 11" flywheel with a 168 tooth ring gear.
Your starter most likely uses a 153 tooth ring gear (for 350). The more common 10.4" flywheels may have the smaller count gear....not sure but worth checking out.

 

The 400 flexplate has a pretty good sized weight on it.

The one on the left is a 350 or "neutral balanced" flywheel, the one on the right is the external balance 400 part

 

Thanks for the answers,
I need a flywheel not a flexplate(stick shift)
Now I know to flip it over and check for a weight.
thanks Russ