68 or 78 differential

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Jul 12, 2014 | 11:09 AM

rworley6641

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From: Elizabethtown Pa

68 or 78 differential

I purchased a 3:55 differential. Date code on driver's side case is L 26 8;
I believe that to be December 26, 1968 or 1978. The drive shaft yoke is 4 1/8+ inches. I believe this to be a later year yoke; older yokes were
3 1/2+; this made me think it was a 1978.

The stamped code on the bottom is 1 AN 25 69 W. I thought there would be an E in that code to indicate an Eaton Posi. In opening the case, I found it to be a posi unit and the ring gear gave the pinion gear as 9 and the ring gear as 32; which divides out to 3:55. After that it gave a 68. So now I think its a 1968; with a later year yoke. Probably was rebuilt or something. Any opinions?

Jul 12, 2014 | 01:21 PM

0Willcox Corvette

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From: Jeffersonville Indiana 812-288-7103

St. Jude Donor '08-'09-'10-'11-'12-'13-'14-'15

The stamp AN indicates 68

**1968-1969 **

AK 3.36:1 Standard (327/350)
AL 3.08:1 Positraction (327/350)
AM 3.36:1 Positraction (327/350)
AN 3.55:1 Positraction (327/350)
AO 3.70:1 Positraction (327/350)
AP 4.11:1 Positraction (327/350)
AS 3.70:1 Standard (327/350)
AT 3.08:1 Heavy Duty Positraction (427)
AU 3.36:1 Heavy Duty Positraction (427)
AV 3.08:1 Positraction (427)
AW 3.08:1 Heavy Duty Positraction (427)
AY 2.73:1 Heavy Duty Positraction (427 Turbo Hydra-Matic)
AZ 3.55:1 Heavy Duty Positraction (427)
FA 3.70:1 Heavy Duty Positraction (427)
FB 4.11:1 Heavy Duty Positraction (427)
FC 4.56:1 Heavy Duty Positraction (427)

**1978 **

OK 3.08:1
OM 3.36:1
OH 3.55:1
OJ 3.70:1

Jul 12, 2014 | 01:45 PM

rworley6641

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From: Elizabethtown Pa

Quote:

Originally Posted by Willcox Corvette

Hey. Thanks, why the larger yoke? It was not standard for 68, correct. Someone must have switched it out.

Jul 13, 2014 | 09:46 AM

tracdogg2

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From: Garland Texas

1968 automatics use the larger 1330 series pinion yoke.
Mike

Jul 13, 2014 | 10:58 AM

rworley6641

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From: Elizabethtown Pa

This is a 9210 pinion yoke; I thought 1970 and before they used a smaller yoke.

Jul 13, 2014 | 11:42 AM

tracdogg2

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From: Garland Texas

All 63-67 used the small 1310 series yoke
68-70 4 speeds used the 1310
68-70 auto used the 1330
71-79 all used the 1330
All 80-82 used the 1310 Dana yoke
Mike

Jul 13, 2014 | 12:17 PM

rworley6641

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From: Elizabethtown Pa

Quote:

Originally Posted by tracdogg2

All 63-67 used the small 1310 series yoke
68-70 4 speeds used the 1310
68-70 auto used the 1330
71-79 all used the 1330
All 80-82 used the 1310 Dana yoke
Mike

I am doing a 1970 convertible restoration; it was a four speed. Hence the smaller yoke, 1310/9210. I want to put the 3:55 from a 1968 I acquired that has the 1330 yoke. I quess I can exchange the yoke/companion flange. Splines on the pinion shaft will need to be a match and the torgue on the companion shaft a certain foot

lbs?

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