Rear end numbers ?

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Oct 8, 2010 | 05:58 PM

...Roger...

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From: Dayton, Ohio

Rear end numbers ?

This is on a 71 , AB M 230 2
370 ratio , Dec. 23rd 1970 .... is this right ? Does the last 2 mean anything ?
Thanks

Oct 8, 2010 | 06:35 PM

Alan 71

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From: Westminster Maryland

Hi Roger,
I believe the 3 digits are a julian date
I believe the last digit refers to the shift... twi-light.
Regards,
Alan

Here's the configuration I'd expect to see:
2 letters.... LR, 3.36:1
Axle plant... W, Warren Motive
Julian date... 12, 12th of January
Posi source... E, Eaton
Shift... 1, day shift

Last edited by Alan 71; Oct 8, 2010 at 06:38 PM.

Oct 8, 2010 | 07:22 PM

#s matching 72

Instructor

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From: Pioneer California

Are those number and letters visible with the differential installed?

Oct 8, 2010 | 09:10 PM

Frogday

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From: Woodinville WA

Quote:

Originally Posted by #s matching 72

Are those number and letters visible with the differential installed?

They are, but can be difficult to see. You just have to get under the differential and look up at the bottom.

Oct 8, 2010 | 09:21 PM

...Roger...

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From: Dayton, Ohio

Thanks Alan , I better take another look.

Oct 8, 2010 | 09:23 PM

shrekviper

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From: Utah

Does that mean that he doesn't have posi?

Mine's more like Alan's (with much more rust), but who knows what my car is made of now. '69 vert,
OAW 244 E1

Oct 8, 2010 | 09:43 PM

GPGG70

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From: Nixa Missouri

Hi roger,
M= 1972 Pontiac of canada.
AB = 3.70:1
Trying to find my julian dates for those years diffs
Hope this helps a little.

Oct 8, 2010 | 10:06 PM

Frogday

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From: Woodinville WA

All 1970-72 differentials were posi.

Alan has it right, but that M must not be an M.

AB - 3.70:1
M - this must be something else, choices are B Buffalo, D Dana, E Eaton, G Chevrolet Gear & Axle, K McKinnon Industries, or W Warren Motive.
230 - August 18th, probably 1970, so it is an early 1971
2 - Second shift

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Oct 8, 2010 | 10:36 PM

GPGG70

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From: Nixa Missouri

Roger,
Any chance you can send a pic? The info I got about the M is from the corvette by the numbers book page 455.

Oct 8, 2010 | 10:46 PM

#10

#s matching 72

Instructor

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From: Pioneer California

[QUOTE=Frogday;1575565902]All 1970-72 differentials were posi.

Alan has it right, but that M must not be an M.

Maybe the Guy or Gal that stamped it got the "W" upside down Thus being "M".....?????

Oct 8, 2010 | 11:01 PM

#11

...Roger...

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From: Dayton, Ohio

Quote:

Originally Posted by GPGG70

Roger,
Any chance you can send a pic? The info I got about the M is from the corvette by the numbers book page 455.

Yes , I'll get one and post it in the morning. Thanks guys

Oct 8, 2010 | 11:46 PM

#12

...Roger...

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From: Dayton, Ohio

This is the best I can do tonight.

Oct 9, 2010 | 02:03 AM

#13

Frogday

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From: Woodinville WA

Looks like a W to me.

Oct 9, 2010 | 02:28 AM

#14

#s matching 72

Instructor

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From: Pioneer California

It's Weak, but it's a W
Sometimes they don't quite hit the stamp hard enough

Oct 9, 2010 | 07:58 AM

#15

...Roger...

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From: Dayton, Ohio

Quote:

Originally Posted by Frogday

Looks like a W to me.

Yep definitely a W , I'm losing it.

Oct 9, 2010 | 08:58 AM

#16

Alan 71

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From: Westminster Maryland

Hi Roger,
Interesting pictures though! Thanks!!
Regards,
Alan

Oct 9, 2010 | 01:24 PM

#17

...Roger...

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From: Dayton, Ohio

OK now that we figured out I'm dyslexic and the M was actually a W :o how does the julian date work for diffs ?

Quote:

Originally Posted by Alan 71

Julian date... 12, 12th of January

How does a 12 = 12th of Jan. ?

Quote:

Originally Posted by Frogday

230 - August 18th, probably 1970, so it is an early 1971

How does 230 = Aug 18th 1970 or 8-18-70 ?
I think the 0 is 70 but I don't get the 23

Oct 9, 2010 | 01:28 PM

#18

Frogday

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From: Woodinville WA

12th day of the year is Jan 12.
230th day of the year is Aug 18.

Oct 9, 2010 | 03:27 PM

#19

Alan 71

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From: Westminster Maryland

Hi Roger
I never looked to see why JULIAN??
"A calender named after Julius Caesar, and started in 46 BC." The 365 day calendar we now use.
I sure feel a lot better knowing that!
Regards,
Alan