Welcome to the site. Please feel free to share some pictures of your ride, good bad or ugly.
3.42:1 is available in the aftermarket. ie Richmond Gear offers a gear set.
Can't offer comment on posi units but will say that I was not overly impressed in a PowerTrax locker that I had in my 70 GTO. It worked awesome but snapped painfully loud on corners.
As far as the posi unit goes, I think there's quite a selection of aftermarket units out there but I've heard guys say an Eaton unit is fine for the street. No experience with anything other than a stock unit myself though.
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1966 Strato Chief 2 door, 427 4 speed, 45,000 original miles
1966 Grande Parisienne, 396 1 of 23 factory air cars (now converted to a "factory" 4 speed)
I guess I'm going to start the junkyard route and then aftermarket. I'm thinking 3.36:1 12 bolt would work well as well ,likely about 2800 RPM @70 MPH with TH350 and 29 " BFG T/A's
dcneric.......................you may have seen this car , it came from Regina
If it's a 12 bolt you will be shopping for 3.31 ratio Les. 3.36 would be 10 bolt. I know, picky picky but might as well have the right numbers if you are shopping!
I don't know how much junkyard success you will have. These things are just getting too old.
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1966 Strato Chief 2 door, 427 4 speed, 45,000 original miles
1966 Grande Parisienne, 396 1 of 23 factory air cars (now converted to a "factory" 4 speed)
That's it..................... have had a few issues with timing and carburetion, bad heads, too much cam and low compression but I have plans to match components up a little better.
Les, I can recomend the Eaton posi unit, my '69's had the same unit for about 20 years now and the only problem's been remembering they need a shot of posi additive to the fluid every few years.
I'm running over 500 hp and ditto on torque, street strip and trailer hauling so you can be assured it's been tested.
I was dealing with exactly this at work today. We have a truck in the shop with diff trouble, 98 with an 8.5". I called around and got prices on the Auburn and the Eaton. The Eaton was only about 75 bucks more than the Auburn and my experience with Auburn was through 90's B bodies. Those Auburns are almost always worn out on the Impala SS's by the time they have 50,000 miles on them, and as stated, non rebuildable. To me the Eaton vs. Auburn is a no brainer and what's posted above confirms it.
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1966 Strato Chief 2 door, 427 4 speed, 45,000 original miles
1966 Grande Parisienne, 396 1 of 23 factory air cars (now converted to a "factory" 4 speed)