Rear end codes upside down. Is it possible
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Joined: May 2011
Posts: 220
Rear end codes upside down. Is it possible
Is it possible that the rear end 2 letter code on my 66 F85 is stamped upside down. I did some research and it says it should be on the passenger axle tube facing the front of the car. Mine is one the correct passenger side axle tube but it facing the back of the car. It says IS but those letters dont mean any thing for any year Olds. SI on the other hand says its a 3.55 rear in 1966. I think that was an option in 66 specifically for towing on an F85. Please let me know what you guys think.
Oldsdruid
Joined: Dec 2007
Posts: 10,617
From: Southside Vajenya
Anything is possible within the realm of the correct part being installed as the car came down the line.
You have to remember these cars were put together by human beings whose primary goal was to get the car built, out the door and sold with a minimum of warranty work. They never considered these cars would be on the road nearly 50 years later.
They had guidelines they were supposed to follow, but I can promise you an upside down stamping was not going to shut the line down. It was simply to show the service organization what was in the car should it need service or be subjected to a recall or testing campaign.
SI codes as non-posi 3.55 gearing for 1966 3300 thru 3800 except wagon. It is listed as a standard option for those cars without J56 heavy duty brakes or Y75 15" wheels. Anti-spin would code as SJ. So I doubt it was specifically tailored for trailering, though it would have been a good choice.
The 66 shop book also states "The differential ratio code letters (1/4" high) are stamped on the right rear inboard side of the axle housing tube" and the accompanying picture clearly shows it on the rear of the passenger side axle tube, a couple inches outboard of the brake line clip.
You have to remember these cars were put together by human beings whose primary goal was to get the car built, out the door and sold with a minimum of warranty work. They never considered these cars would be on the road nearly 50 years later.
They had guidelines they were supposed to follow, but I can promise you an upside down stamping was not going to shut the line down. It was simply to show the service organization what was in the car should it need service or be subjected to a recall or testing campaign.
SI codes as non-posi 3.55 gearing for 1966 3300 thru 3800 except wagon. It is listed as a standard option for those cars without J56 heavy duty brakes or Y75 15" wheels. Anti-spin would code as SJ. So I doubt it was specifically tailored for trailering, though it would have been a good choice.
The 66 shop book also states "The differential ratio code letters (1/4" high) are stamped on the right rear inboard side of the axle housing tube" and the accompanying picture clearly shows it on the rear of the passenger side axle tube, a couple inches outboard of the brake line clip.
Registered User
Joined: Dec 2010
Posts: 857
From: crawfordville, florida
On the chassis line (at least at the Lansing Assembly Plant) the chassis was upside down when assembled. Only the HD rear ends would have the two letter code upside down and they would appear to be indepeneintly stamped. All non-HD rear ends were already stamped from the rear axle plant.
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