It is all about the numbers - How to find your Serial Number

First thing is to figure out what you own. What is your base vehicle? M151, M151A1, or M151A2. There are lots of numbers you can find, they will lead you to manufacturer and when it was made.

There are 3 numbers you can find

1. Military Registration Number - On the sides of the Hood. Vehicles from the mid 1970s on, may have this number painted under the hood or on the dash in front of the passenger. 
2. Manufacturer Serial Number - On the Data Plate, on the dash. *
3. Manufacturer Serial Number of the "uni-body" - On a plate or stamped in the body or.... on the body in various locations.

For the most part, with some exceptions listed below, Your Mfg SN is the same (or with some additional info) as the Registration number on the hood of your M151.  * Willys & Kaiser had a MFG SN that had no relationship to the US military registration number. See some detail below. 

Provided By: Ken (Mutt Guru)

US Army REGISTRATION NUMBERS - AKA, HOOD NUMBERS 

From World War II, the US Army has used more than one numbering system.
The WWII numbering system for jeeps began with the weight class as in 2012345, the initial "20" signifying 1/4-ton. This system continued right up to 1960.

From 1959, a new system was introduced, comprising numbers and a letter.............as in 2A 1234. It also brought in a revised 1/4-ton classification beginning with "2" The initial "2" signified 1/4-ton, so no real change from the WWII system. But immediately after the "2" came a letter, starting with "A" and working through the alphabet. When the number reached 2A 9999, the next letter was used... 2B 0001 etc.... some letters were NOT used because they could be confused with numbers (such as I and O).
A typical early hood number would appear as 2B 1234. Late-model M38A1s were mainly "2A-series".

In 1968, a new numbering system was introduced which incorporated a "Year of Delivery" into it.... as per 02A 12368 - 12345. (a reversal of the WWII system that began with "20").
"02" again meant 1/4-ton truck, the "A" was used as part of an alphabetical sequence, the "123" would be followed by "124" etc, but the "68" stayed the same all that year. The letter used would change to the next-in-sequence once the numbering reached "999". Example 02A 999 would be followed by 02B 001. The actual year-of-delivery would change, but the changeover could result in one vehicle with hood number 02D 99668 being followed by 02E 99769. as long as you remember that the last two digits were "the year", it was a straightforward system, and for mutt researchers, it was THE BEST numbering system.
When the first A-Z alphabetical sequence was used up, a second letter was added, as per 02AB 12370 - 45678 (70 being the year of delivery).
The "45678" was the MFR Serial Number of that specific vehicle, followed, as you'd guess, by 45679 for the next vehicle etc.
A typical hood number would appear as 02GM 12370 (the second sequence of numbers did not appear on the hood but did appear on the data plate).
In mid-1973, with the introduction of the emission control systems, the numbering changed yet again, this time to the 6-letter+digit system.
Instead of vehicle size and type being designated as "02" for jeep-type trucks, the new system used "NB", (Gama Goats were "NG" etc).
This system remains in place to this day . the combination of weight-class (NA, NB etc) along with the use of (at first, numbers), then a combination of numbers and letters, followed by a combination of letter x letter x letter results in a possible combination of thousands of vehicular issues per type classification.

Contract Number: DA-20-018-ORD-21125

25 June, 1959

September, 1960 to February, 1961 for 4,050 vehicles. 

Government Cost: $2,423.00 ( Cost listed is cost charged to the Government. Ford actual cost was $3,205.00 ) 

First Vehicle Delivered 09/15/60

   First serial number & registration / hood number = 2B6487

   Last serial number & registration / hood number = 2C0537

Ford Motor Co. - Built at Livonia Transmission Plant in Michigan.

The first production MUTT was made in April 1960

Contract Number: DA-20-018-ORD-23240

28 April, 1961, to at least March 1962 for 13,124 vehicles.

Government Cost: $3,550.00 (body built by Budd Co. for Ford at a cost of $303.50)

   First serial number & registration / hood number = 2C1268

   Last serial number & registration / hood number = 2D5316*

Ford Motor Co.- Built at Livonia Transmission Plant

Contract Numbers: DA-33-019-ORD-3941 

21 May 1962 to at least 12-1963 for 14,625 vehicles.

Government Cost: $2,780.00

   First serial number & registration / hood number = 2D9267*

   Last serial number & registration / hood number = 2E9018*

Willys Motors Inc

Contract Numbers: DA-20-113-AMC-0846-(T)

14 December 1962 to June, 1964 for 9883 vehicles

Government Cost: $2,631.00.00 per vehicle

   First serial number & registration / hood number = 2E8835*

   Last serial number & registration / hood number = 2F8674*

Kaiser Motors

* ( asterisk ) Means the number was derived from actual data plates or military information. It is not the published government or factory data. It is not nececarilly the first or the last "actual" number.

Willys Motors Inc. & Kaiser Jeep Corporation (Name change during contract, around January 1964)

Last straight M151 built May 1964 by Kaiser (Published data) - Correction or??? I own an M151 built by Kaiser with a DOD of 06-64 that is a STRAIGHT M151 possibly built May 64 but delivered June with a Registration number of 2F8391. So original data is incorrect.  

Willys & Kaiser Mfr Serial number (on data plate) was not the Registration number like it was on the Ford produced vehicles. Example: 7405-25327 (the suffix changed vehicle to vehicle)

Unkown = USMC, US NAVY or US AIR FORCE registration numbers. To date I have seen no evidence that any branch besides the US ARMY used the "straight" M151.
 

Contract Number: DAAE 06-68-C-0001

26 September 1967 

First production vehicle was delivered February 1970

24,503 vehicles

First serial and hood number = 02CX0770-????? -Last = 02  

Ford Motor Co.

There are NO "production" M151A2s made prior to January 1970, any M151A2 made prior to 1970 was a test vehicle. 

Contract Number: DAAE 07-71-C-0103

Awarded 16 February 1971

AM General Corp.

Built at the former Studebaker military truck plant in South Bend, Indiana

Contract Number: DAAE07-76-D-0002

AM General Corp.

Contract Number: DAAE07-77-C-3404

AM General Corp.

Contract Number: DAAE07-79-D-5016

AM General Corp. 

Contract Number: 30-5-GP576

Unknown Date

2K1656  (05-66)   to   2K3992  (NA)     Known spread of date & registration numbers) 

Rock Island Arsenal - Modified base M151A1s to M718s

Contract Number: 30-6-GO233-01-30-I8

Unknown Date

03-67 336172  (03-67)   -   03-67  336245  (03-67)   Known spread of date & registration numbers USMC) 

Red River Army Depot - Modified base M151A1s to M718s (Both Army and USMC vehicles were modified by (RRAD).

Contract Number: DAAE 06-68-C-0001

Unknown Date 

(09-68)  02F23268-00232  Known spread of date & Registration number)  

Not a separate contract to the original base vehicle, Built as an M718 by Ford

Unknown Production 

Contract Number: DAAE 07-71-C-0103

Unknown Start

02A00372-10002  to NB0G71-10837   -   Known  spread of Registration numbers 

Not a separate contract to the original base vehicle, Built as an M718A1 by AM General 

Unknown Production

Contract Number: DAAE 07-77-C=3404

Unknown Start

510478 C718-00192 to 510500 C718-????? Known spread of Registration numbers USMC) 

Not a separate contract to the original base vehicle, Built as an M718A1 by AM General (Both Army and USMC vehicles were built under the same contract). 

Unknown Production

Contract Number: A1-Z1500-A1-30

2G5773  (09-65)   to   2G6802  (09-65)  Known spread of date & Registration number)

Rock Island Arsenal - Modified base M151A1s to M718s.

Ford delivered to the Rock Island Arsenal 1,660 M-151-A1C units by 6/65 

Contract Number: 30-6-GP995-01-30-I8

2N2692  (06-67)   to ??????  (??-??)     Known spread of Registration numbers 

Rock Island Arsenal - Modified base M151A1s to M718s.

 Contract Number: DAAE 07-71-C-0103

Unknown Start 

02A00272-10200   (ukn date)   to   NB0GJ7-11122   (ukn date). Known spread of registration numbers 

Not a separate contract to the original base vehicle, Currently I believe all US Military M825s were built by AM General between 1972 & 1974

The US Navy had a small contingent of M825s at the US base in Iceland

Early TOW vehicles are seen in Vietnam on early Ford M151A2s

The later TOW Vehicles were built at Depots such as:

ANAD (Aniston Army Depot) - MCLSB (Marine Corps Logistics & Supply Base) Pacific "Barstow California"

A plain batch of M151A2s were taken and the "kits" for the TOW launcher or TOW Carrier were added to the base vehicle. They did not receive a new M number like the M825. But simply a plate giving the whole "jeep" a new NSN and Ordnance part number, along with a date of build.