Please help confirm 12 bolt axle stamping is legitimate. COZ 0302 G 2 with E below

wicka5

New Member
May 28, 2002
7
Escondido, CA USA
Looking for expert help. I have a 12 bolt differential on a 1970 Camaro Z28 that I purchased in 1988 (original San Diego car). Am bringing car out of storage after 35 years. I just got around to looking at stamping on passenger side axle. The stamping is COZ 0302 G 2 with E below. So, the COZ is 3.73:1 and 0302 is March 2nd for 1970. G is Detroit Gear Axle and E would be for posi. However, the Z is stamped harder. Is that normal? Also, the E is below. Is this all legitimate or could someone have re-stamped the axle or changed axles. The car was built 1st week of April per cowl tag and build sheet. Also, are those welds on axle factory? I paid a very reasonable $500 for car in 1987 and it is real Z28 as I found two build sheets. However, the gears in the differential are not 3.73:1. Looks like highway gears were installed by prior owner. The two build sheets were found under driver side back seat carpet and one above gas tank. Any expert help is appreciated.
 

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  • 1970 Camaro Z28 VIN 124870L514531 build sheet  JPG format.jpg
    1970 Camaro Z28 VIN 124870L514531 build sheet JPG format.jpg
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  • Close up COZ.jpg
    Close up COZ.jpg
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ronzz572

Veteran Member
Lifetime Gold Member
Feb 8, 2007
2,512
imperial pa
The stamp looks legitimate to me. I'm basing that on examples I have seen. I have seen the letter Z stamped that way before. The date stamp aligns well with the date code on your car. I feel the rear is original to your car.
 

wicka5

New Member
May 28, 2002
7
Escondido, CA USA
The stamp looks legitimate to me. I'm basing that on examples I have seen. I have seen the letter Z stamped that way before. The date stamp aligns well with the date code on your car. I feel the rear is original to your car.
Thanks so much for your feedback. Much appreciated. Now, I just have to find the correct 3.73:1 gears and install.
 

Rosster

Veteran Member
Gold Member
Mar 1, 2020
1,104
I’m guessing the CO is a gang stamp and they add the final letters/numbers when the diff is assembled. My COO has the last letter out of line too.
FB200DC5-9C79-488B-A60D-4921959A170F.jpeg
 

clm69z28

Veteran Member
Oct 29, 2011
416
encinitas ca
Looking for expert help. I have a 12 bolt differential on a 1970 Camaro Z28 that I purchased in 1988 (original San Diego car). Am bringing car out of storage after 35 years. I just got around to looking at stamping on passenger side axle. The stamping is COZ 0302 G 2 with E below. So, the COZ is 3.73:1 and 0302 is March 2nd for 1970. G is Detroit Gear Axle and E would be for posi. However, the Z is stamped harder. Is that normal? Also, the E is below. Is this all legitimate or could someone have re-stamped the axle or changed axles. The car was built 1st week of April per cowl tag and build sheet. Also, are those welds on axle factory? I paid a very reasonable $500 for car in 1987 and it is real Z28 as I found two build sheets. However, the gears in the differential are not 3.73:1. Looks like highway gears were installed by prior owner. The two build sheets were found under driver side back seat carpet and one above gas tank. Any expert help is appreciated.
Hey Wicka5, what a small world. My '70 HO RS Z was also sold at Courtesy Chevrolet in Mission Valley. I'm not too far away over in Encinitas; looks like we even have similar garage setups.
20190314_174056.jpg


As to rear end stamps, here's the one out of my car.

IMG_5244.JPG
 

john Gialanella

Veteran Member
Oct 15, 2008
570
Bloomfield N.J.
Wow you paid only $500.00 for that very nice Z-28. That is the steal of the Century. Good luck finding 3.73:1 gears. I bought a 1970 SS 396 L-78 numbers matching in December 1988 and it cost me $10,500.00. I sold it to Chuck Sharin in Dember 2001.
John.
 




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