im told that this
383 crank needs to have a 400 balancer&flywheel

i've found a 400 harmonic balancer

but i dont know any place where i can find a flex plate to go with it.


I thought all automatic flywheels were the same for any small block?

do any of you guys know about any thing like this?

400 flex plate is counter balanced. You should be able to get one from any parts house.

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Dave

There is a fine line between "hobby" and "mental illness".

BUT you need to know 100% for sure if your 383 was internal balance or external balance. If it's an aftermarket upper end 4340 crank it's 'typically' internal, if it's a reground stock 400 crank, or any of the cast steel aftermarket cranks it's 'typically' external (but that's not a 'rule' just a typical configuration)
NAPA sells them for around $40ish, or any GM parts department will get you one (for about twice the NAPA price)