Differemtial ID

[Tom L.]

I have a friend with a diff. that he wants to identify so he can sell it. The stamped numbers on the bottom of the case don't make a lot of sense, specifically the 2 letter code that identifierd the gear and application. Here's what we have:

Casting #: 3899143
Date code: K 18 7
Stamp, or what I can make of it: O (or C) K 347 W 7 E

I attached some pictures that may help. Thanks!!

[Joe L.]

Re: Differemtial ID

I have a friend with a diff. that he wants to identify so he can sell it. The stamped numbers on the bottom of the case don't make a lot of sense, specifically the 2 letter code that identifierd the gear and application. Here's what we have:

Casting #: 3899143
Date code: K 18 7
Stamp, or what I can make of it: O (or C) K 347 W 7 E

I attached some pictures that may help. Thanks!!

Lynn------


It's unfortunate that the stamped prefixing alpha characters are the most unreadable since those are the most important in IDing the unit. However, I expect that the code is "OK". Combining that with the cast date code on the carrier housing, "K 18 7" which could either represent November 18, 1967 or November 18, 1977, I'd say that what you have here is a November, 1977 manufactured carrier assembly of gear ratio 3.08:1 installed on an early 1978 Corvette.

If you count the teeth on the ring gear and it turns out to be 37 teeth, that would help confirm the above.

[Tom L.]

Re: Differemtial ID

Thanks Joe, I did count the teeth and calculated it and it is a 3.08 gear, but didn't mention that.

I didn't know that the date codes did not differentiate decades. Is there any way to tell if it is a '67 or '77 case? Seems that there would be a way. Thanks again!

[Joe L.]

Re: Differemtial ID

Thanks Joe, I did count the teeth and calculated it and it is a 3.08 gear, but didn't mention that.

I didn't know that the date codes did not differentiate decades. Is there any way to tell if it is a '67 or '77 case? Seems that there would be a way. Thanks again!

Lynn------


By the stamped code, is the only way. Different codes were used for different model years.

[Gary R.]

Re: Differemtial ID

Post a picture of it, showing the bearing caps and posi. If original it will have no cast in tabs on the caps, the posi would be the small window. A 77 would have the tabs and the tear drop window. Other then stamped numbers the 77 is a better unit.

[Wayne M.]

Re: Differemtial ID

Lynn -- here's another way to identify the "big window" later posi case from the earlier "postage stamp" window. On the newer one, the end numbers cast around the bearing should read: ED 32297 AW (for a 3-series ring gear); and if the 1967 case (again, 3-series) it should be: EDB 30117. Of course, these cases and carriers could have been swapped over the last 30-40 years .

[Gary R.]

Re: Differemtial ID

This is a 68. Typical of 65-68, although not all have been hit by a pinion. This was caused by a previous rebuilder. I'd say 50% of all original 65-68's I open up have cracked posi's compared to less then 10% of the 69-79's. You can see the caps as well.




Here is a 69-79 Tear drop type