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| | | | Joined: Oct 2008 Posts: 121 Shop Shark | | Shop Shark Joined: Oct 2008 Posts: 121 | Found out this afternoon, while backing out a steep driveway, that my 55 2nd has a posi ( limited slip
), evident with the 2 black strips left on the pavement. Are they common? Looking to swap it out for economical gears.
Last edited by hb32; 06/07/2009 9:35 AM.
1955 Chevy 3100
| | | | | Joined: Feb 2002 Posts: 12,029 Cruising in the Passing Lane | | Cruising in the Passing Lane Joined: Feb 2002 Posts: 12,029 | there was no positrac in 55 - the standard 1/2T rear is 3.90, with the OD trans it was 4.10 .... aftermarket 3.38 gears are available near you, don't know how well they'd do with the 235 around town Bill | | | | | Joined: Oct 2008 Posts: 121 Shop Shark | | Shop Shark Joined: Oct 2008 Posts: 121 | there was no positrac in 55 - the standard 1/2T rear is 3.90, with the OD trans it was 4.10 .... aftermarket 3.38 gears are available near you, don't know how well they'd do with the 235 around town Bill I will jack in the am but sure looks like a posi(limited slip) with the 2 patches of tire left behind. May have been swapped out in the last 54 years. Checked with the aftermarket available in my area and $1000 kind of scares me. Working on a GMC rear option.
Last edited by hb32; 06/07/2009 9:35 AM.
1955 Chevy 3100
| | | | | Joined: Nov 2008 Posts: 355 Shop Shark | | Shop Shark Joined: Nov 2008 Posts: 355 | it was more than likely a limited slip rear posi's didn't really come out till the muscle cars
1937 1/2 ton
| | | | | Joined: Oct 2008 Posts: 121 Shop Shark | | Shop Shark Joined: Oct 2008 Posts: 121 | it was more than likely a limited slip rear posi's didn't really come out till the muscle cars Agreed and I do know the difference. More of a loosely used term.
1955 Chevy 3100
| | | | | Joined: May 2006 Posts: 8,351 'Bolter | | 'Bolter Joined: May 2006 Posts: 8,351 | Positraction is the Chevrolet name for a limited slip differential, just like how Chrysler used Sure-Grip for theirs. The first year for Positraction in a GM truck was '59, the used the Spicer 45 GMC axle in both Chevy and GMC trucks wehn equipped with that option. An Eaton based Positraction differential came out in '60 for Chevy, and was used until '62, although I have sen code listings for it in '63 as well. Seems those Posi 3rd members are soemwhat rare, I've only ever sen one.
I'm going to venture to say that if you do indeed have a Posi dif, it is most likelya later rearend out of a '70s truck, when they became more common.
Bill Burmeister
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