Where is it?

[lee]

I have a 71 block in my 68 charger and was wondering is there a serial number stamped some where on this block does anyone know.

[mikepmcs]

On the slant six engines it is located just below the cylinder head on the passenger side of the block.
 
On the "A" and the "LA" engines it is stamped on the drivers side front of the block just below the cylinder head.
 
On the "B" engines it is stamped on the top of the block near the distributor.
 
On the "RB" engines it is stamped on top of the block forward of the intake manifold on the drivers side.
 
The stamps may include the engine size and also a series number for the year.
 
A=1965...B=1966...C=1967...D=1968...E=1969...F=1970...G=1971...H=1972...J=1973...4?=1974

 
There could also be a stamping "HP" or "HP2" designating High performance.

[hemigeno]

I have a 71 block in my 68 charger and was wondering is there a serial number stamped some where on this block does anyone know.

By "serial number", do you mean a partial VIN referring to the car that motor came in originally?

[lee]

It is a 383 engine

[lee]

Yes where is the number on the block that tells me what it came out of before

[hemigeno]

Yes where is the number on the block that tells me what it came out of before

We talked about that very thing in this thread:

http://www.dodgecharger.com/forum/index.php/topic,15110.0.html

Here's the question and reply from that thread:

2. I currently have a 383 big block in my charger. How can I tell what my block come out of? I found some numbers on the block, can these help?

It totally depends on what year of 383 you have.  '67 and earlier 383s, as well as '68 LP 383's will have no clues to go by.  '68 HP and '69+ 383s will have at least a partial VIN.  You might get lucky, in that if you have a '69 model year 383 that was assembled before December of 1968 (or somewhere around there), there will be a full VIN stamping.  That will tell you what the body style of the car the motor was originally installed in.  Apart from that, the partial VIN stamping will only tell you what the model year of the car was, what assembly plant the car was made at, and what the sequential VIN is.  If it came from a plant that only made specific types of cars (e.g. Jefferson, which only made C-body cars), you might be able to rule out some types of cars, but you still couldn't say for certain what it was.  There is no record that I am aware of where you can cross-reference a VIN to what type of car it was.  Many plants made multiple body styles, and there is no particular rhyme or reason to their VIN sequences.  A station wagon VIN might follow a Hemicar.

Like Chryco said, there are some clues that you can get from the ID pad below the distributor.  That will tell you what model year your block was made for, the assembly date, and whether it was a 2- or 4-bbl 383 motor.  Whether it is an HP or not is really all you need to know, to be honest - and that is stamped on the ID pad by the distributor.