iroc22

I'm in an argument with a guy about where the term 'posi' actually came from. I said it's a GM marketing name for their limited slip units made in the 60s (by who??) and he claims that Eaton has had the name trademarked since the 50s before GM even used the name. What's your take on this?

This all came up from discussing possible rear ends for thirdgens. I don't think it's worth swapping in any 60s corp rear ends because of all the bracketry but he's an old timer and he guesses that they are toughest

TKOPerformance

My understanding is that the term "Positraction" is a Chevrolet trademarked term. It is used widely to refer to a limited slip differential. Ford liked the term "Traction Lock", AMC used "Twin Grip", and other GM divisions used a myriad of other names to describe the same thing.

GM built their own posi units in the 60s.

Swapping an actual 60s vintage axel into a 3rd gen is lunacy. Way too much fabrication, and those rears are typically worn out anyway and need a total rebuild, including new axels.

Bolting in a modern 12-bolt from Moser, Curie, or others isn't a bad idea though. The Ford 9" will still be stronger though.

iroc22

Ah so GM did build their own LSD's in the 60's. Because Eaton has 'Posi' trademarked for their curent LSD's (not sure when they did that) and I believe the first production year that GM used the term 'Posi-Traction' was in 1957.

Yeah you're tellin me that it's complete lunacy. Now I just have to convince him that it is.....