Engine Code- somethings amiss

[BlueCollarRon]

so on the back of the motor it reads
3970010

and on the front it reads
v0405tbd

When i go to www.nastyz28.com I find this information

Flint, April 5,1979   350   conv. cab,m/t, fed   L LS9   165   4    K-10 to 2500



Everything I can find tells me that it is a 350,
the motor runs with an externally balanced flexplate and harmonic balancer.  
umm?

[KY..Rob]

Is this a stock Engine? I think the 400 and the 454 BB used external balance. Someone might have swapped in some parts not knowing what they had. Your Engine code also comes up as a 1968 327,  Maybe these older Engines used an external balance. The 327 had a pretty big bore, same as the 350 I think.

[BlueCollarRon]

Thanks for the reply.  Maybe u could take a look at these and tell me what u think?  I am not sure exactly how to determine 400 vs 350.  I know 350 is internally balanced and 400 external.  I know this flexplate has weights,and it looks to me like this harmonic balancer is not balanced.  being everything is blue, target master 350???  Oh and notice the other pictures, somebody rebuilt this before right??

[1980c10]

Maybe I'm missing something but:
350 block, 400 crank = 383
Check the casting number on the crank;
3951529 400 70-80 Cast Iron,externally balanced
39411182 350 69-85 Truck Forged Large Journal

[1980c10]

Oh and notice the other pictures, somebody rebuilt this before right??
Those look like marks for re-assembly, so most likely.
The orange sticker looking thing on the bottom of the oil pan may have been a sticker for warranty or something, can you read it?

[BlueCollarRon]

thanks that information is very helpful.  I'll see if I dont have a picture of it tonight, if not I'll check it out tomorrow at the shop.

The "orange sticker thing" is an old oil pan heater.

That would be cool, a 383 stroker!

[1980c10]

let us know what you find out.
btw; I would put a frost plug type heater in the engine if you don't already plan on it.

[BlueCollarRon]

its a 350.  internally balanced. yea i use a circ a block and oil pan heaters.