Decode 1964 differential-Help
Thread Starter
Pro
Joined: Oct 2013
Posts: 520
Likes: 281
From: Nor-Cal California
Decode 1964 differential-Help
I'm trying to decode my 64's rear end as to which gearing it has. I've searched the internet and can't find much help.
The numbers I find on it are:
on the bottom facing the rear of the car upside down is: GM4
opposite this on the top is 8880808 if read upside down...
if read right side up it is 8080888
I scraped it well but it's hard to tell if the 8's are 3's.....and can't really tell if it's up or down-confused? me too....
These are #'s that are cast in-NOT stamped #'s
Am I looking in the wrong place? Are there #'s on the sides or front somewhere? Are they stamped like engine #'s or cast in? Somebody please enlighten me. Thanks
The numbers I find on it are:
on the bottom facing the rear of the car upside down is: GM4
opposite this on the top is 8880808 if read upside down...
if read right side up it is 8080888
I scraped it well but it's hard to tell if the 8's are 3's.....and can't really tell if it's up or down-confused? me too....
These are #'s that are cast in-NOT stamped #'s
Am I looking in the wrong place? Are there #'s on the sides or front somewhere? Are they stamped like engine #'s or cast in? Somebody please enlighten me. Thanks
Team Owner
Joined: Jul 2006
Posts: 22,192
Likes: 4,180
From: Kannapolis NC
I'm trying to decode my 64's rear end as to which gearing it has. I've searched the internet and can't find much help.
The numbers I find on it are:
on the bottom facing the rear of the car upside down is: GM4
opposite this on the top is 8880808 if read upside down...
if read right side up it is 8080888
I scraped it well but it's hard to tell if the 8's are 3's.....and can't really tell if it's up or down-confused? me too....
These are #'s that are cast in-NOT stamped #'s
Am I looking in the wrong place? Are there #'s on the sides or front somewhere? Are they stamped like engine #'s or cast in? Somebody please enlighten me. Thanks
The numbers I find on it are:
on the bottom facing the rear of the car upside down is: GM4
opposite this on the top is 8880808 if read upside down...
if read right side up it is 8080888
I scraped it well but it's hard to tell if the 8's are 3's.....and can't really tell if it's up or down-confused? me too....
These are #'s that are cast in-NOT stamped #'s
Am I looking in the wrong place? Are there #'s on the sides or front somewhere? Are they stamped like engine #'s or cast in? Somebody please enlighten me. Thanks
AZ = 3.55 (from a 427)
122266 = stamped Dec 22, 1966
Team Owner
Joined: Oct 2000
Posts: 38,897
Likes: 1,926
From: Washington Michigan
I'm trying to decode my 64's rear end as to which gearing it has. I've searched the internet and can't find much help.
The numbers I find on it are:
on the bottom facing the rear of the car upside down is: GM4
opposite this on the top is 8880808 if read upside down...
if read right side up it is 8080888
I scraped it well but it's hard to tell if the 8's are 3's.....and can't really tell if it's up or down-confused? me too....
These are #'s that are cast in-NOT stamped #'s
Am I looking in the wrong place? Are there #'s on the sides or front somewhere? Are they stamped like engine #'s or cast in? Somebody please enlighten me. Thanks
The numbers I find on it are:
on the bottom facing the rear of the car upside down is: GM4
opposite this on the top is 8880808 if read upside down...
if read right side up it is 8080888
I scraped it well but it's hard to tell if the 8's are 3's.....and can't really tell if it's up or down-confused? me too....
These are #'s that are cast in-NOT stamped #'s
Am I looking in the wrong place? Are there #'s on the sides or front somewhere? Are they stamped like engine #'s or cast in? Somebody please enlighten me. Thanks
Pro
Joined: Sep 2007
Posts: 673
Likes: 58
From: Calgary Alberta
You're looking at the casting # of the rear carrier cover; and yes, it's upside down.
It's 3830303. Others may chime in with the other numbers of interest, one casting near the nose of the diff, above the rib, and the stamping on the bottom flange where the rear cover bolts to the main carrier case. There's also a casting date below the driver side output yoke.
c
It's 3830303. Others may chime in with the other numbers of interest, one casting near the nose of the diff, above the rib, and the stamping on the bottom flange where the rear cover bolts to the main carrier case. There's also a casting date below the driver side output yoke.
c
Team Owner
Joined: Jul 2006
Posts: 22,192
Likes: 4,180
From: Kannapolis NC
Here are the codes for 63-64
CA 3.36:1 Standard Manual Transmission or Powerglide
CB 3.36:1 Positraction Manual Transmission or Powerglide
CC 3.55:1 Positraction 4-Speed
CD 3.70:1 Positraction 4-Speed
CE 4.11:1 Positraction 4-Speed
CF 4.56:1 Positraction 4-Speed
CJ 3.08:1 Positraction 4-Speed
CX 3.70:1 Standard Close-Ratio 4-Speed
CZ 3.08:1 Standard Wide-Ratio 4-Speed
CA 3.36:1 Standard Manual Transmission or Powerglide
CB 3.36:1 Positraction Manual Transmission or Powerglide
CC 3.55:1 Positraction 4-Speed
CD 3.70:1 Positraction 4-Speed
CE 4.11:1 Positraction 4-Speed
CF 4.56:1 Positraction 4-Speed
CJ 3.08:1 Positraction 4-Speed
CX 3.70:1 Standard Close-Ratio 4-Speed
CZ 3.08:1 Standard Wide-Ratio 4-Speed
Race Director
Joined: Jan 2007
Posts: 13,671
Likes: 14
From: Down on the bayou in south Louisiana
St. Jude Donor '10
Why not mark the driveshaft and count how many times it must be turned to make the rear wheel turn one full turn? As old as these cars are the gears may have been changed and may not be what is stamped. M2C
Team Owner
Joined: Feb 2003
Posts: 54,121
Likes: 9,435
From: Sitting in his Nowhere land Hanover Pa
2024 C2 of the Year Finalist - Unmodified
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Thread Starter
Pro
Joined: Oct 2013
Posts: 520
Likes: 281
From: Nor-Cal California
Here are the codes for 63-64
CA 3.36:1 Standard Manual Transmission or Powerglide
CB 3.36:1 Positraction Manual Transmission or Powerglide
CC 3.55:1 Positraction 4-Speed
CD 3.70:1 Positraction 4-Speed
CE 4.11:1 Positraction 4-Speed
CF 4.56:1 Positraction 4-Speed
CJ 3.08:1 Positraction 4-Speed
CX 3.70:1 Standard Close-Ratio 4-Speed
CZ 3.08:1 Standard Wide-Ratio 4-Speed
CA 3.36:1 Standard Manual Transmission or Powerglide
CB 3.36:1 Positraction Manual Transmission or Powerglide
CC 3.55:1 Positraction 4-Speed
CD 3.70:1 Positraction 4-Speed
CE 4.11:1 Positraction 4-Speed
CF 4.56:1 Positraction 4-Speed
CJ 3.08:1 Positraction 4-Speed
CX 3.70:1 Standard Close-Ratio 4-Speed
CZ 3.08:1 Standard Wide-Ratio 4-Speed
It is stamped- CA 10 which makes it a 3:36
according to the above codes that would make it a 3.36:1 standard Manual Transmission....It now has a 4 speed in it and the rear is Posi, so something got changed or?....
Le Mans Master
Joined: Mar 2009
Posts: 7,992
Likes: 3,974
From: Cold Harbor, VA
look again a little further across the casting for the rest of the date code.
There has to be some more digits for a full date such as 10 ** 63 or 1 0* 64
or something. The digits are usually widely spread apart as in the example shown.
And yes, if there is a posi in the box now, then someone made some changes to the original CA box.
There has to be some more digits for a full date such as 10 ** 63 or 1 0* 64
or something. The digits are usually widely spread apart as in the example shown.
And yes, if there is a posi in the box now, then someone made some changes to the original CA box.