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I recently replaced the 350 in my 69 Lemans vert with a 455 and I am just starting to tune, but it is obvious that the factory 2.78 open gear is going to make things very hard on the tires. It is even breaking a tire loose and spinning it on auto downshifts to 1st until I let off (TH400 with 13" converter.) So now considering posi options.

I really like the road gear for this car- its a cruiser, not a drag racer, and I want to be able to be able to take it for a drive several hours down the highway without turning the heck out of the engine. Can I get a posi unit for the 2.78 gear? If not, can a 2.93 gear be found for the posi units that are pretty readily available? I don't think that I want to go any higher than that, am I thinking wrong?

Pontguy, I think with or with out posi you going to spin the heck out of any ratio...lol.

We can get you a good reconditioned 2 series posi... I will have to check stock.

As you stated a 2.93 or 3.08 would be a good choice and YES the posi units are available in the aftermarket too.

We have 3.08 gears and the posi unit that matches. I do not think we have had a 2.93 in 10 years from a PONTIAC rear...Buisk 68-70 yes. AGAIN let me ckeck stock. Jim

Thanks Jim, I have had a bunch of Pont 350's and a few 400's over the years, some of them pretty strong, but this is my first 455 and the bottom end torque is a bit shocking. I guess I could go with a 3.08 but was hoping not to. I have run 3.23's and 3.55's and know I definitely don't want to go there- I'd be happier with the 2.78 even with all the spinning. Everyone seems to wants the big gears, but my experience is that they are not really much fun in a street car without an OD trans.

No big rush on this, but lets see what you can come up with. I am working on it hard but just replaced about everything mechanical on the car (except for the gear) and still have a bunch of debugging and tuning to do. So right now just looking at options. We are probably looking at some time during the next couple of months or so.

I will keep the eye and ears open for you. Jim

I am sure something will come in soon.

Sounds good. Let me know if you find something for the lower ratios, if not I will likely give you a call to discuss the 3.08 options down the road a bit. Walt

Hey Jim, I have a line on an original Pont 2.93 gearset. Just to confirm- no problem getting a posi carrier for this ratio, right? Should be the exact same carrier used for 3.08 - 3.23? Walt

Yes, They fit that carrier 2.93-3.23 ... If you can get pictures of the gears I will look at them just to be sure they are for your rear if you like. Jim

The guy selling the gears is offering a return guarantee so I am just about ready to cut a deal with him. I should have pictures coming.

He mentioned that the ring gear uses the mid-'69 and up 7/16" bolts instead of the earlier 3/8" bolts. Any issues with that?

And now lets talk seriously about options for a good posi carrier and the parts needed to set up my rear end. Options, pricing...

Walt

7/16 bolts will limit you to 1969-172 factory stock GM gears only. You want 3/8 for aftermarket and early most common gears. Watch out you might be sending that back. Jim

All aftermarket posi units and gears are 3/8 the 7/16 is kind of a odd ball set-up for the 8.2 10 bolt rears.

The 3/8" factory bolts will have 11/16" hex head and the 7/16" bolt (left hand thread) will have 3/4" hex head bolt.

Hope this helps. Jim