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72 Cheyenne K20 02-10-2026 05:40 PM

Quadrajet Date Question
 
1 Attachment(s)
I have a Rochester Quadrajet number 7043208 with a date code of 1538 on my truck when I bought it. All of the engine is original except for this.

From the number 7043 it’s from a 73’ but the date code indicates 153rd day of 68’ or 78’.

Does anyone have a clue or seen this happen before?

Thanks, Scott

geezer#99 02-10-2026 09:56 PM

Re: Quadrajet Date Question
 
Since the casting number starts with a 7 and not a 1 that would indicate the carb is pre 1976. The number 1 at first place started in 76.
Your 8 would be 1968 then.

Corts60 03-15-2026 06:51 PM

Re: Quadrajet Date Question
 
1965-69 carbs would've started with a 702 or 703. Since yours starts with 704, it is a 70-75 carb. The 4th digit is the year. In your case a "3" is 1973.

breakdown:
704
3 = 1973
2 = federal emissions
0 = Chevy
8 = even number usually means auto trans, but not always

As for the date being 1538, most likely this was a factory service replacement carb that was installed in 1978 or later, maybe under warranty.

72 Cheyenne K20 03-15-2026 08:19 PM

Re: Quadrajet Date Question
 
Hi guys and thanks for the replies.

I understand the cast dating but wanted to know if anyone has any reasoning for the model cast number to not match the date cast number.

7043 = 1973
1538 = 1968 or 1978

The last number in the date should be a 3 to match the 7043

So, I was thinking maybe they got the date mixed up and it should be 1583 instead ?

Thanks Scott

Corts60 03-16-2026 03:25 PM

Re: Quadrajet Date Question
 
Quote:

Originally Posted by 72 Cheyenne K20 (Post 9426506)
Hi guys and thanks for the replies.

I understand the cast dating but wanted to know if anyone has any reasoning for the model cast number to not match the date cast number.

7043 = 1973
1538 = 1968 or 1978

The last number in the date should be a 3 to match the 7043

So, I was thinking maybe they got the date mixed up and it should be 1583 instead ?

Thanks Scott

Yep, I hear ya, the model cast date and Julian date are different when the carb is a factory service replacement. Meaning the original carb probably had a repeat issue and the dealer installed this carb as a replacement. So, 1538 probably indicates the year this carb was installed, or 1978.


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