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Differential drain plug

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Old Apr 17, 2023 | 09:23 PM
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Default Differential drain plug

Just curious, Which C1 years did not have a differential drain plug? What was the reasoning for not having a drain?
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Apr 18, 2023, 09:32 AM
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Originally Posted by Plasticman
62, because GM was "cheap"..

Plasticman
To your point, the late Tom McCahill once wrote to the effect that the reason GM included $0.50 bumper jacks with passenger cars was that they ran out of the $0.25 ones.
Old Apr 17, 2023 | 09:25 PM
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62, because GM was "cheap"..

Plasticman
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Old Apr 18, 2023 | 09:32 AM
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Originally Posted by Plasticman
62, because GM was "cheap"..

Plasticman
To your point, the late Tom McCahill once wrote to the effect that the reason GM included $0.50 bumper jacks with passenger cars was that they ran out of the $0.25 ones.
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Old Apr 18, 2023 | 12:33 PM
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Originally Posted by jim lockwood
To your point, the late Tom McCahill once wrote to the effect that the reason GM included $0.50 bumper jacks with passenger cars was that they ran out of the $0.25 ones.

LOL!

And, thanks for the reminder of McCahill. He was the main reason I subscribed to Mechanix Illustrated back in the day. I still go onto the Internet Archive now and then to read his work. I loved (and still love) the Q&A column.
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Old Apr 18, 2023 | 12:53 PM
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The 56 and 62 Corvettes (and pass cars) did not have a drain plug--------------------------------Although, I have added several.
The 55-64 pass car axle housings were MOSTLY the the same (except for welded-on brackets for springs). From what little I have learned SOME, repeat, SOME VERY, VERY early 62 pass car and Corvette axle housings had a drain plug.But otherwise, 61 was the last year for a drain plug. Eliminating the drain plug probably saved GM $.05/car.
ALLLLLLLLLLLLLLLL my cars without a drain plug have had a magnetic plug added.




This is the 55-6 and 62-64 pass car style housing, and 56 and 62 Corvette (ALL 57-61 rears had a drain plug) style housing with a drain plug added.







This is a later GM style cast iron rearend center section with a drain plug added.


















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Old Apr 18, 2023 | 02:47 PM
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Can somebody tell me the size of the drain plug? I need to change my washer out and need one on hand to eliminate any unnecessary oil loss. Also, what is the best type?
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Old Apr 18, 2023 | 02:57 PM
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Originally Posted by Duck916
LOL!

And, thanks for the reminder of McCahill. He was the main reason I subscribed to Mechanix Illustrated back in the day. I still go onto the Internet Archive now and then to read his work. I loved (and still love) the Q&A column.
I savored every road test he ever wrote.

And let's not forget Mimi.... another reason to have subscribed.
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Old Apr 18, 2023 | 03:54 PM
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Originally Posted by 59BlueSilver
Can somebody tell me the size of the drain plug? I need to change my washer out and need one on hand to eliminate any unnecessary oil loss. Also, what is the best type?
I use the same size magnetic drain plug that was used on Chevy oil pans, 1/2in, fine threads.
On cast iron rearend center sections, a magnetic 1/2in pipe thread plug can be used, but I just do not prefer them. Same magnetic drain plug that was used on the M22 Muncie, and which I install on all M20-M21 Muncie cases that did not get a drain plug..


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