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Positraction In A '62 340HP

Old 12-12-2018, 12:09 AM
  #41  
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Can you get under it to get numbers off of the rearend center case?
If so, we need numbers from BOTH sides of the case.
Driver side will have something like this. The main numbers to see will be the casting date which will begin with a letter (A-L).



The passenger side will have a STAMPED code beginning with 2 letters and 3-4 numbers, as below.








It is very probable that a 64 wagon will have either a 3.36 or a 3.08 ratio.
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Old 12-12-2018, 12:49 AM
  #42  
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From what I've read, I thought it'd be a 3.36. If I can get a good 350hp-400hp out of the 327, I think a 3.36 may be OK with the 4sp, but I'd prefer a 3.55.
I'm having the pumpkin removed tomorrow. The car will need to be jacked up.
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Old 12-12-2018, 10:24 AM
  #43  
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Originally Posted by 6T2Vette View Post
From what I've read, I thought it'd be a 3.36. If I can get a good 350hp-400hp out of the 327, I think a 3.36 may be OK with the 4sp, but I'd prefer a 3.55.
I'm having the pumpkin removed tomorrow. The car will need to be jacked up.
As I have pointed out 800 bazillion times over the years, this type rearend was installed behind 63-64 425hp/409 engines with 4sp in full size Chevys. Unless regularly beat and abused at the strip with sticky slicks, they held up quite well. Since MOST people today do not abuse these rears like they did over 50yrs ago, then it should be fine for a lifetime if properly rebuilt.
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Old 12-12-2018, 10:56 AM
  #44  
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Originally Posted by DZAUTO View Post
As I have pointed out 800 bazillion times over the years, this type rearend was installed behind 63-64 425hp/409 engines with 4sp in full size Chevys. Unless regularly beat and abused at the strip with sticky slicks, they held up quite well. Since MOST people today do not abuse these rears like they did over 50yrs ago, then it should be fine for a lifetime if properly rebuilt.
The car is laying flat on a trailer so removing the part will take a little bit of effort. If it's a good non posi unit, should I then ask my fab guy to remove the gusset and turn it into a Posi rear end? Rebuilding this into a 3.56 Posi rear end would have some appeal to me as a resale feature.
Bob
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Old 12-12-2018, 12:09 PM
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When a portion of the gusset (as shown here) of a NON-posi case is removed, then the ONLY, ONLY, ONLY difference between a modified non-posi case and a posi case is the lack of the big P on the non-posi case. And the portion of the gusset that is removed MUST BE REMOVED all the way to the wall, because the posi unit it a very close fit.









This is the inside of a P-case (posi), and the difference between the non-posi case and the P-case, is only the remaining portion of the gusset in the non-posi case.


Unless a person is adamantly insistent about having a center case with the big P, then once a posi unit is added to a non-posi case, it is just as much a posi rear as it is in a P-case!!!

Last edited by DZAUTO; 12-12-2018 at 12:12 PM.
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Old 12-12-2018, 11:58 PM
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Originally Posted by DZAUTO View Post
When a portion of the gusset (as shown here) of a NON-posi case is removed, then the ONLY, ONLY, ONLY difference between a modified non-posi case and a posi case is the lack of the big P on the non-posi case. And the portion of the gusset that is removed MUST BE REMOVED all the way to the wall, because the posi unit it a very close fit.









This is the inside of a P-case (posi), and the difference between the non-posi case and the P-case, is only the remaining portion of the gusset in the non-posi case.


Unless a person is adamantly insistent about having a center case with the big P, then once a posi unit is added to a non-posi case, it is just as much a posi rear as it is in a P-case!!!
And just to throw a little more gasoline on the fire....the posi unit pictured above is the early style, identified by the shallow V that the cross shaft rests in -about a 135 degree angle. The late 60 and up posi's had a 5 stack clutch pak instead of 4 to the side, and the V for the cross shaft is about 90 degrees. Supposedly it was better. And speaking of the big P, i understand that the thin P was originally in Corvettes, while the thick P was passenger car. And then there was this
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Old 12-13-2018, 01:22 AM
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Originally Posted by vettsplit 63 View Post

And just to throw a little more gasoline on the fire....the posi unit pictured above is the early style, identified by the shallow V that the cross shaft rests in -about a 135 degree angle. The late 60 and up posi's had a 5 stack clutch pak instead of 4 to the side, and the V for the cross shaft is about 90 degrees. Supposedly it was better. And speaking of the big P, i understand that the thin P was originally in Corvettes, while the thick P was passenger car. And then there was this
Hmm, I made a statement I'd read that long "P" type Posi's were Corvette. I was contradicted, but I didn't state that the Posi I have in my '56 BelAir is the one with long skinny P, and I was told they were very collectible among 'Vette collectors. It looks the same as the one I have in my '62.
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Old 12-13-2018, 03:07 PM
  #48  
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The third member number is 3789812 with a short P instead of the long skinny P.
Date appears to be E363.
It is on. 63 BelAir station wagon.
Can it be used as a Posi as is on my 62 vette?
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Old 12-13-2018, 03:36 PM
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6T2, I have a Corvette (thin P) posi with 3.36 gears in it I am going to be getting rid of in the next week or so. I had a numbers correct one built for my car. It is in great shape and runs great, just have to get it out of the car. PM me if you are interested in it. It is an 812 with an Aug 31, 1961 casting date.

Bill

Last edited by 69ttop502; 12-13-2018 at 03:37 PM.
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Old 12-13-2018, 04:49 PM
  #50  
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This is a Canadian (NOT, repeat, NOT a USA part) posi case. It was commonly used in early 60s type Canadian GM cars, such as Pontiacs, with a Chevy driveline.
These posi cases were NOT installed in USA built Chevys.



There were TWO USA plants that made these early rears: Detroit Gear and Axle and the Buffalo (NY) plant.
The Detroit posi rears had the THIN P and the Buffalo posi rears had the thick P.

The thin P case was used in BOTH, repeat, BOTH Corvettes and full size pass cars.
The thick P case was used in ONLY full size pass cars.
Thus, theoretically, thin P cases should be more common---------------------------and after over 50yrs of working on old Chevy rears, I have seen more thin P cases.




Last edited by DZAUTO; 12-13-2018 at 06:36 PM.
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Old 12-13-2018, 04:58 PM
  #51  
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Originally Posted by vettsplit 63 View Post

And just to throw a little more gasoline on the fire....the posi unit pictured above is the early style, identified by the shallow V that the cross shaft rests in -about a 135 degree angle. The late 60 and up posi's had a 5 stack clutch pak instead of 4 to the side, and the V for the cross shaft is about 90 degrees. Supposedly it was better. And speaking of the big P, i understand that the thin P was originally in Corvettes, while the thick P was passenger car. And then there was this
Here is a comparison of an early (57-59) posi unit and a late (60-62 for Vettes, -64 for pass cars) posi units. The shallow V in the case is early and the deep V is late posi.
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Old 12-13-2018, 05:23 PM
  #52  
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What I have in the '63 BelAir wagon is the same as the bottom pic. I assume it is a 3.36, but I want to use it as a 3.55 Posi in my '62 'Vette. I am assuming I can do a direct swap without any mods, correct?
Bob


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Old 12-13-2018, 05:38 PM
  #53  
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What I have in the BelAir Station Wagon is the same as the bottom pic. I assume it is a 3.36. I am also assuming I can install this unit in my '62 'Vette as 3.55 Posi without any mods to the case. Am I correct?
Bob



Last edited by 6T2Vette; 12-13-2018 at 05:40 PM.
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Old 12-13-2018, 06:13 PM
  #54  
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I hope the OP doesn't go shopping for a carrier and get a case instead..
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Old 12-13-2018, 06:36 PM
  #55  
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Originally Posted by MikeM View Post
I hope the OP doesn't go shopping for a carrier and get a case instead..
Mike, Im planning on buying an Eaton differential. Is that what you were wondering about?
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Old Yesterday, 09:15 AM
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The differential which includes the ring gear, differential gears, cross shaft and clutch pack is enclosed in a case. The Easton unit is the case.

The case is installed into the carrier along with the pinion shaft and other bearings.

Just trying to avoid future confusion.

Last edited by MikeM; Yesterday at 09:16 AM.
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