Finding the real age - trying to compare serial numbers with other M39s

My 1973 M51A2 indeed a lot older than I was told when I bought it. Both the engine and the truck itself have tag shields mentioning "overhauled 1973". The name of the truck is given as Kaiser Jeep Corporation, which was active only from 1963 to 1970, after that it became AMC.

CARNAC was able to tell me the history of the truck from 1973 to 1988, which corresponds with the hood numbers I found. After 1988, probably it was shipped to the POMMS depot in the Netherlands without being in active duty anymore. Nothing he found from before that date.

I now am trying to figure out, if possible, how old the truck really is and what was its history before 1973. I already knew the engine was older. According to a shield on the engine, it was overhauled in January 1973, at the USA Maintenance Plant SG. Any idea what-where that is?




The casting of the engine shows 1 14 65. Could this be the manufacturing or contract date?

Cleaning the tag shields in the cabin this September, I found that one barely readable shield mentioned the overhaul date march 1973. Until now, I never paid attention to this shield (please no comments). That mentions that the truck was overhauled in March 1973.



My serial number is 5123 - 12649

Does anybody with an M5x has a serial number close (both below and above) to mine? If so, I can start narrow it down. If you don't want to put your number online, please PM me.


Any other tricks I could use, ways how to find this out, maybe from old archives from the maintenance plant where it was overhauled?

Don't know if it will work on yours but all my 809 series the front spring hangers had the same date stamped as my titles.

Never heard about that, will check when I am back home tomorrow or Thursday.

Also, quite a few components will be date stamped. 'Go Seek'.

It was probably twice overhauled. Once for sure in early 1973, once maybe in 1988 before or after arrival in the Netherlands, since it disappears from the archives around that date for that hood-unit number.

Looked like the 73 overhaul date said "GSA Maint Plant SG", that would be General Services Administration Maintenance Plant SG. Since it was in Europe, that might stand for "Southern Germany" or perhaps "Stuttgart" - just a guess.

I am not sure the truck was in Europe before 1986. According the hood number from 1973 to 1986, the truck belonged to the 368th Engineer Battalion with headquarters in Londonderry, New Hampshire. I don't have complete information yet but I did not find reference to them being in that time in Europe.

Floridianson said:

Don't know if it will work on yours but all my 809 series the front spring hangers had the same date stamped as my titles.

Click to expand...

Do you have a pic from this so I know where to look and how it looks?

In some other threads, I read that what I call serial number also in some of the 5-tons could contain information about original production year and body type. And that the serial numbers of the older trucks are actually shorter, with the second part of the number being a "registration identification"?

Anybody has a clear and definite answer on this?

No pic at this time it's just the front spring hanger will have a date of manufacture on it.

serial number comparison

wasn't close to the truck yet, hopefully I can check tomorrow.

And now for something interesting.

I checked the VIN Info threads for 2009 and 2010 completely, and 2012 partly. And some 5-tons offered for sale where the SN was mentioned. I found 28 M39 5-tons, and checked the manufacturing dates against the serial numbers.

SN with less than nine numbers
I found four trucks with short serial numbers that were manufactured between 1958 and 1963. A fifth truck with short SN was mentioned as 1968, but this truck has been overhauled, so it could be also from early 1960s. A sixth truck mentions 1967, but its date plate was not original, with in the space for contract no mentioned SN xxxxx, with eight numbers.

SN with nine numbers
SN starting with 52... one truck 1964, a second truck has 1967, but the date plate looks like overhauled truck
SN starting with 95... or 96..., nine numbers in total, year of manufacturing 1967 - 1968 (16 trucks):

SN starting with the letter M followed by eight numbers,
SN starts with M72 .... year 1969 (2 trucks ) and later (1976, 1 truck)


I will check the other VIN threads later and update the numbers.

One thing is clear, that in at least two cases, the military data mention years of manufacturing that in reality are the years of complete overhaul, with the actual truck being older. In one case, CARNAC found as date of MFD 1962, while the date tag on the truck mentioned 1954. In my case, the military data base mentions 1973 as year of manufacturing, while tags on the dashboard and engine mention 1973 as year of overhaul.

The first 800 series trucks rolled off the assembly line in 1969. I REALLY don't think Kaiser Jeep was building M39 series trucks concurrently or after the 800 series trucks. Lots of people are misguided by overhaul dates, just as you were.

You probably are right, but they could run parallel for some time, one or two years maybe. Kaiser would start with the first 800s and still have their contract for the M39 to fulfill. However, by the time they were taken over in the early 1970s by AMC it would definitely have stopped already.

So for those wanting to know the real history of their M39, probably all dates after 1969 are suspect and should be checked if it is not the overhaul date.

In my list, one M54 A1C is mentioned as 1976 but has a serial number that is 227 lower than a 1969 M54 A1C.
Similar my M51 A2 has 1973, but that is definitely wrong and the serial number starts with 5123 while another M52 starting with 5224 is dated 1967. According to the SN, mine should be from somewhere between 1964 and 1967.

Update: 41 M39 SNs found in VIN threads 2008 - 2012

I now completed the Vin threads from 2008 through 2012. Included also are some trucks offered for sale and SN provided to me by PM from SteelSoldiers owners.

I now have SNs and date of manufacturing of 41 M39 5-tons.

SN with less than nine numbers
Eight trucks with short serial numbers. Six were manufactured between 1958 and 1963. A seventh truck with short SN was mentioned as 1968, but this truck has been overhauled, so it could be also from early 1960s. The eighth truck mentions 1967, but its date plate was not original, with in the space for contract number was mentioned "SN xxxxxxxx" (eight numbers).

SN with nine numbers starting with 51.. or 52..
Four trucks have SNs starting with 51 or 52.
SN starting with 51.. until now only my truck. Manufacturing date according date shield and CARNAC is 1973. However, this is year the truck and engine were overhauled, truck must be older.

Three trucks have an SN starting with 52... Two of them have 1964 and 1965 as dates, the third one has 1967, but the date plate looks like overhauled truck.

SN with nine numbers starting with 95... or 96...
Twenty-four trucks have SNs starting with the number 9.
Nineteen trucks had SN starting with 95; 18 of those had dates from 1966 to 1968, one truck had 1971. Interesting is that the dates do not follow chronologically following the SNs; for example one SN starting with 95271.... had as date 1966, while the lower 95231.... had as date 1968.

Five trucks started with 96. Four of those were from 1967 and 1968, while one mentioned 1952. This is clearly an error, the serial number is wrong for that early period, and I do not think that there were already M51 A2s in 1952.

SN starting with the letter M followed by eight numbers,
One 1969 truck had SN starting with M7231...., four others started with M7251, with dates ranging from 1969 to 1972.

Question
The M39 5-tons were produced mainly by International Harvester and Kaiser, with Mack and Diamond T making smaller numbers. Are the serial numbers linked to a specific manufacturer, like the SN starting with 95 is Kaiser and 96 is IH?

Very simple first conclusion based on what I found.
In the period 1951-1963, numbers are short and -at least for me- without clear structure. Since 1964 (the oldest number in this line I have) to 1967 it is nine numbers starting with 5, from 1966 to 1968 it is nine numbers starting with 9. The 5 and 9 series SN seem to overlap in 1966 and 1967. Since 1969, the numbers start with M72.

There are no serial numbers starting with any of the other numbers.

Trivia
The information shows the following truck types
M51: 7
M52: 15
M54: 15
M55: 1
M543: 3

Basic version: 5
A1 version: 6
A2 version: 30

Oldest according date shield or military information: 1952
Youngest: 1976

No trucks from 1959-1962; 22 trucks from 1967-1968 (53.7%).

Trucks were the serial number clearly indicates a different date of manufacturing than is provided by date tag or title or military database: eight (19.5 %)