Differential identification

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May 2, 2006 | 03:41 PM

StingrayDK

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From: Denmark

Differential identification

Since im having everything apart for the offset T/A and douple mounted fiberspring installation, ive decided to change the oil on the diff aswell. Ive heard that you need to add a special additive with the oil for the posi diff, but since everything else on the car is unoriginal i figure the diff is aswell.

I found these casting numbers on it: 3876476-N + 3871375 and it was stamped : AP 7 7 65.

Can anybody tell me what diff this is and what oil and additive i should use?

Thx

Anders

May 2, 2006 | 04:17 PM

Easy Mike

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What year?

I use GM positraction fluid (big bottle) and GM positraction fluid additive (little bottle).

May 2, 2006 | 05:13 PM

StingrayDK

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Im not sure.

The body is 69 the frame is 68.

I have no idea what year the diff is

Last edited by StingrayDK; May 2, 2006 at 06:01 PM.

May 3, 2006 | 03:50 AM

StingrayDK

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Ttt

May 3, 2006 | 08:18 AM

Easy Mike

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AP indicates 4.11:1 for 68 and 69 if that's what you have. I suspect the 7 7 65 is a date code.

May 3, 2006 | 08:54 AM

StingrayDK

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Thanks.

I turned the t/a yoke one full rotation and the driveshaft yoke turned just over 4, so the 4.11:1 sounds about right.

Is it safe to say thats its a posi unit and i should add the additives to the oil?