<VV> Good block number?

[djtcz at comcast.net]

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Message: 1 
Date: Sat, 25 Jan 2014 19:39:31 -0500 (GMT-05:00) 
From: Grant Young <gyoungwolf at earthlink.net> 
Subject: <VV> Good block number? 

A customer sent me an engine block stamping of 3786091. My tech guide chart says there should be a 5 where the 0 is, but he 
is adamant that it is correct. Can someone help me out with this? 
Thanks, 
Grant 
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Is it a stamped number or a casting number? 
A Google search ( " 3786091 corvair" ) suggests block halves with that exact >> casting << number have been the subject of questions a few times in years gone by. 

here is one - 
http://www.vv.corvair.org/pipermail/virtualvairs/2010-November/106353.html 

Speaking generically sometimes a casting ( or a forging ) with a particular integrally formed number ( as opposed to stamped in numbers) can be machined or processed to create many significantly different parts. 
I have not checked, but I'd kind of expect left and right block halves to have different casting numbers since the as-cast parts are completely different. 

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The big engine bearing books often have tables listing the "forging" numbers of crankshafts and connecting rods for each engine to help prevent selecting the wrong bearings. 
This tends to add to confusion since some rods and cranks are cast, not forged. 
pages 59-63 here - 
http://www.mahle-aftermarket.com/C125790900540AC0/vwContentByUNID/BAE05A140D0A0082C1257C0C0040D639/$FILE/EB-40-14.pdf 

forging number (because it's a forged crank) with raised, kind of battered numbers 
http://www.angelfire.com/ca4/CorvAIRCRAFT/cranknbr.jpg 

casting number - Here is a Pontiac crank. There is a crisp, raised casting number on one throw. The big N on the other throw indicates it is cast of nodular iron. 
http://pontiacworkshop.com/wp-content/uploads/2012/12/SA233_3-5.jpg 

Another Pontiac crank with cast-in identification it is made of some flavor of GM's fancy ArmaSteel. 
http://pontiacworkshop.com/wp-content/uploads/2012/12/SA233_3-4.jpg 

stamped engine number ( with ZF possibly looking a little doctored) 
http://lh3.ggpht.com/_77ksmJ3F1jU/Sps4gyIkEaI/AAAAAAAACB0/R1u0XNTxxNw/s800/IMG_4413.JPG 

cast numbers visible in block just above the oil pan flange in this pic - 
http://www.n56ml.com/corvair/01012505.jpg 

The big engine bearing books often have tables listing the "forging" numbers of crankshafts and connecting rods for each engine to help prevent selecting the wrong bearings. 
This tends to add to confusion since some rods and cranks are cast, not forged.