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Kurt_Laughlin · ***Power User*** Offline Joined: Jan 24, 2006 Posts: 577

The likely reason for the different numbers on the rear is that one is the build number or place on the assembly line while the other is the Ordnance serial or acceptance number. You can imagine how the first vehicle in the line finishes up and gets SN 1, the second SN 2, and so on, but what happens if a defect is discovered in a vehicle on the line? The likely scenario is that it gets pulled out, repaired, and re-inserted. That knocks the two number series out of alignment until after the defective vehicle gets accepted.

Evidence shows that early vehicles have little or no difference between the two numbers but that it grows as the numbers increase.

KL

silviop15 · ***Power User*** Offline Joined: Oct 03, 2015 Posts: 415

Makes sense. The number under the rear, right, lifting hook is 176.

TrevorLarkum

So presumably the lower of the two numbers is the build number and the higher is the acceptance number?

Kurt_Laughlin · ***Power User*** Offline Joined: Jan 24, 2006 Posts: 577

- TrevorLarkum

So presumably the lower of the two numbers is the build number and the higher is the acceptance number?

I'd say just the opposite. If hulls 201 thru 205 get taken out of line, serial number 201 will be assigned to build number 206. The position, as on M41s and M42s, is more definitive.

KL

silviop15 · ***Power User*** Offline Joined: Oct 03, 2015 Posts: 415

Agreed.

Kurt_Laughlin · ***Power User*** Offline Joined: Jan 24, 2006 Posts: 577

I had to run to work today so here is some further discussion. On M41s and M42s it has been determined that the left number is the BN, the right number is the Ordnance SN:
www.com-central.net/in...m41+serial

So, here's a sample:
M41
BN - SN
377 - 378
980 - 980
1091 - 1086
2510 - 2506
2920 - 2925
2985 - 2982
3010 - 3007
3023 - 3019
3225 - 3225

M42
BN - SN
304 - 303
537 - 537
1183 - 1181
1621 - 1620
1689 - 1677
1673 - 1686

KL

vagabond

So on the example photos from Fort Carson that I posted earlier in this thread, the Build Number would be the LEFT stamping of 1266 and the Ordnance SN would be the RIGHT stamping of 1268 - correct?

silviop15 · ***Power User*** Offline Joined: Oct 03, 2015 Posts: 415

No.

The LEFT number, matches the serial number on the dataplate, which matches the number stamped behind the dataplate on the hull.

Kurt_Laughlin · ***Power User*** Offline Joined: Jan 24, 2006 Posts: 577

- vagabond

So on the example photos from Fort Carson that I posted earlier in this thread, the Build Number would be the LEFT stamping of 1266 and the Ordnance SN would be the RIGHT stamping of 1268 - correct?

That's an M114. You can't extrapolate the positions from M41s and M42s. I included those examples to address the "which is usually lower?" question.

KL

vagabond

Ok. I mistakenly applied Kurt's example of M41/42 rear plates to M114s.

Let's see if I have this correct for M114s now:

The number below the LEFT rear lifting hook corresponds to the SN.

The number stamped below the RIGHT lifting hook might be the Build number?

Is it strange that the build number would be lower than the SN? For Silvio's M114 the SN is 180 and the RIGHT rear stamping is 176.

Similar situation on the Ft Carson examples - the Left number is lower than the right on both M114 displayed there.

silviop15 · ***Power User*** Offline Joined: Oct 03, 2015 Posts: 415

Seems about right.

Since when does the army make sense? Razz

Kurt_Laughlin · ***Power User*** Offline Joined: Jan 24, 2006 Posts: 577

Greater than, equal to, and less than are all possible. For example:

BN - SN
1 - 1
2 - 2
3 - 3
4 - Oops, throws a track during the test drive.
5 - 4
6 - Oops, engine blows a gasket during the 50 mile run-in.
7 - 5
Track re-set, BN 4 put back into the line
4 - 6
8 - 7
Engine repaired, BN 6 put back into the line
6 - 8
9 - 9
10 - 10

Or let's say that the Ordnance inspector only applies SNs at the end of the shift, and does it by walking from one end of the parking area to the other:

BN, as parked
104 - 100 - 101 - 103 - 102
SN, as assigned
100 - 101 - 102 - 103 - 104

KL

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