GarrettandGus

Someone sold me a differential for cheap claiming that it is a posi-trac. The writing on it says "TRAC- LOK" and I'm not really familiar with differential types. I don't have my jeep with me now to compare it to my stock one. The guy claimed its a posi that was in his jeep when he purchased it and he is selling it to get better milage and less tire wear. Anyone heard of this?

glass3222

Posi, or Positraction, is a brand name for chevy limited slip differentials (LSD). Trak-Lok is chysler/jeeps name brand. Posi is a common "slang" term for all LSDs.

In the 1950s and 1960s many manufacturers began to apply brand names to their LSD units. Packard 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: Q2
American Motors: Twin-Grip
Buick: Positive Traction
Cadillac: Controlled
Chevrolet/GMC Positraction
Chrysler: Sure Grip
Dana Corporation:Trak-Lok or Powr-Lok
Ferrari: E-Diff
Fiat: Viscodrive
Ford: Equa-Lock and Traction-Lok
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
Oldsmobile: Anti-Spin
Pontiac: Safe-T-Track
Porsche: PSD (electro-hydraulic mechanical)
Saab: Saab XWD eLSD
Studebaker-Packard Corporation: Twin Traction
TVR: Hydratrak
Yukon Gear & Axle: Duragrip

tinytrax78

mine is welded it is called twin spin