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ASEMaster35yrs, GMC Technician
Category: GM
Satisfied Customers: 2095
Experience:  ASE Certified since 1972,Master Auto tech,Heavy Truck,4 years GMC Tech
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Small block chev, rear of engine #3970010 pass front #MLO6800

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Small block chev, rear of engine #3970010 pass front #MLO6800 what is it ?

Hi, glad to be of help. i'm going to need all three identifiers to properly identify this engine. Can you clean off and chalk the id on the right front passenger side just below the head and send a picture of it and post it here? The MLO6800 does not appear to be in the correct order.

Also, can you tell me the date code.


Casting Date
Small block casting date is located on driver side rear of block on flange forward of bellhousing. Big block on the right side of engine above the oil pan rails.

Casting Date Example: E038 - (E = Month, 03 = Day, 8 = Last digit of model year (1978)).

Month: A = Jan, B = Feb, C = Mar, D = Apr, E = May, F = Jun, G = July, H = Aug, I = Sep, J = Oct, K = Nov, L = Dec


Here are the three identifier locations



For your casting number, here are the possibilities:


Casting number

3970010....302.....69....4...Z-28 Camaro
3970010....327.....69....2...Trucks and industrial
3970010....350...69-80...2 or 4





car & Truck 2 & 4-Bolt Most common


The closest I can come to the engine ID is




air cond.








s h/p




Chevy II




m/t,4 spd





The engine id on the pad should have 4 numbers prior to the suffix code at the end. The suffix code will be either two or three letters. Anything produced 1970 and later will have three letters. 69 and prior will have two.


If your suffix is ML the engine is a 327ci with 275hp from a 1967 camaro or X body with air conditioning or it could be from a 1968 chevy II SS 327ci with 325hp.

The date code on the engine will verify which one.

ASEMaster35yrs and 4 other GM Specialists are ready to help you
Customer: replied 5 years ago.
Drivers side rear of block #2 GM MEXICO ,(NNN) NNN-NNNNCenter of block rear isJ. 21. 80., Front pass side of block only has MLO 6800 . Only numbers i can find .Oh yea the needle on the clock is pointing at what looks like an N. Hope you can find out what it is?

Ok, this is a 1981 350ci crate engine made in mexico on October 21, 1980 at noon.

This is an over the counter engine and no way to tell what horsepower but they normally come with 250 or 275hp.

GM dealerships sold replacement engines called "Target master" from the late 80's to early 90's. That's what this is. The MLO6800 is merely a serial number.


A number of crate motors made by GM in Mexico, may have an "M" or "ML" prefix stamped into the front pad of the block followed by a series of numbers which is the serial number of that particular crate replacement motor. You may also see a raised casting on the block or heads of "Hecho en Mexico" which means "Made in Mexico". Many of the new GM crate motors are being made in Mexico. Later model crate engines, sold over the counter by Chevrolet or GM Performance Parts, may have different prefix code identifiers stamped in to the front pad on the block, such as "ZZ3" or three letter codes such as "XXA".


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