Posi-Traction

[BillR. CLC # 29203]

What was the first year when Posi-Traction was available?
Thanks.
Bill R.
CLC # 29203

[Mike Josephic CLC #3877]

I had it in a '63 GM (not a Caddy) it was an option.
However, I recall that the first year GM offered this
was 1957.

The system was primitive and on a slippery hill I
remember it caused the rear end to sway rather
violently from side to side as the clutches kicked
in.  It could get you up a steep hill here in Western
PA but it was far from ideal.

Mike

[The Tassie Devil(le)]

Wasn't the Cadillac LSD called a Controlled Differential?

I have one out of a '66 SDV.

Bruce.

[Clewisiii]

It was listed as an option on 61. There is even a column on the build sheets for it.  But none were built that year.  So I assume 62 Cadillac would be the first.

[35-709]

Believe GM first offered it in 1957.
From Wikipedia ---
In the 1950s and 1960s many manufacturers began to apply brand names to their LSD (Limited Slip Differential) units. The Studebaker-Packard Corporation pioneered the LSD under the brand name "Twin Traction" in 1956, becoming one of the first manufacturers. Other factory names for LSDs include:

Alfa Romeo: Q4, Q2
Audi: Quattro, Quattro with Sport Differential (rear axle)
American Motors: Twin-Grip
Buick: Positive Traction. Gran Sport models used the term "Limited-slip (differential)"
Cadillac: Controlled
Chevrolet/GMC: Positraction
Chrysler: Sure Grip
Dana Holding Corporation:Trak-Lok or Powr-Lok
Ferrari: E-Diff
Fiat, Lancia: Viscodrive
Ford: Equa-Lock and Traction-Lok
Hyundai: HTRAC
International: Trak-Lok (clutches only) or Power-Lok (clutch and ramping engagement process)
Jeep: Trac-Lok (clutch-type mechanical), Tru-Lok (gear-type mechanical), and Vari-Lok (gerotor pump), Power Lok
Lincoln: Directed Power
Maserati: Equ-Tor
Nissan: GT LSD
Oldsmobile: Anti-Spin
Pontiac: Safe-T-Track
Porsche: PSD (electro-hydraulic mechanical), Porsche Torque Vectoring/Plus (PTV/Plus, combined electro-hydraulic mechanical and brake-based type; rear axle only)
Saab: Saab XWD eLSD
Studebaker-Packard Corporation: Twin Traction
Toyota: LSD
TVR: Hydratrak
Yukon Gear & Axle: Duragrip
Mercedes: ASD, AMG Rear-Axle Differential Lock (active differential on select FR-based AMG/S models; pure mechanical variant also present on select non-S AMG models)

[BillR. CLC # 29203]

Mike, Bruce, Carl and G. Newcombe,
Thanks for your reply and insight.
Bill R.
CLC# 29203