1957 365 engine

[Burt6666]

Hi,how does one tell if it's an "early" or "late" Engine ? Mine is 76X6438.Thanks in advance !!!

[Roger Zimmermann]

76X is for Serie 60S and 62 without A/C and without dual carbs. If you know how many cars were produced that way, you have the answer. A different approach is with the VIN which is stamped on the engine on the passenger side, just before the cylinder head.
In my opinion, you have an early engine.

[fishnjim]

Several ways.   The "build" sheet will have the original engine number on it, if it's still in there.
Can get one from GM Heritage Center for your VIN for $50.   
What you show is the model info from the body plate, not the VIN or engine number.  VIN is in several locations.   Engine block and door frame plate.
The engine number is stamped on the block.   See attached for location.
They'll have different parts on them depending when they were produced, so needed for some things, like carbs, internals, etc.

[Roger Zimmermann]

What you show is the model info from the body plate, not the VIN or engine number. 

Sorry, 76X...is the engine number.

[Burt6666]

Looks like early....engine number is 006463

[fishnjim]

Sorry, blew it.   My bad.   
When it said '57, I was thinking the VIN should be the all numbers kind, which changed in '58 to include the letter.    Weren't enough sequence numbers given for engine, 4 vs 5?
You'd have to look at the production #s for '57 and compare, without the build date.   I don't have that info handy.   Usually in the part list if it's a change.   I think it's in the interchange manual.   I found some others there and posted.   I'll look when I get a chance.

[fishnjim]

I show you should have a VIN number and engine number the same.   like 5760xxxxx, or 5762xxxxx.   The 76X is stamped on the rear of block and applies as Roger indicated.   VIN on the block pad at the front of the head.   Same as on the door plate if # matching.
You didn't say which model you have, as 76X applies to both series 62 and 60 spec.   It's the low HP(285) 4 bbl 365.
They made about equal numbers of 60s and 62 models, around 25000 ea.   So if the sequence number is 06463, then it's earlier in the production.   But would need to check the production records that they were produced simultaneously and not sequentially, as each type is made under a separate starting number. 57600001, 576200001,577500001.   So one model could be earlier or later depending when it was assembled.   I don't see any way it being "late" at 6463/25000.
It's in the shop manual but I found this in the interchange.

[fishnjim]

I was down doing some wiring had the '57 manual out.   
Calling for 6 digits.

[Burt6666]

Thanks guys...engine is now at machine shop for rebuild !!!