Anyone have a spare set of 3.08 gears they are willing to part with? All the aftermarket seems to be 71 and up and I have a 68. I have the standard 8.2 10 bolt, looking to upgrade from my 2.56.

I tried looking for new gears but got a headache for my trouble. The used 3:08 gears are out there but are getting expensive. Plus you need the right carrier. I read your other thread about changing over and now I guess you figure used gears are better than none. I agree. I have installed used gears plenty of times and if you know what you are doing it is not a big deal. But the carrier is a problem. A whole rear axle would be easier to find. If I was looking for one I would want a posi carrier. The 8.2 posi uses the old style cone clutches and they are usually shot or about to die. An open rear is OK but with a 400 I would want a posi. The only real benefit to the 8.2 BOP rear is the way the axle bearings are retained with the four bolts at the axle ends. The Chevy style C-clips are garbage. That said, there is another path. I have a 1979 Trans Am 3:08 disc brake rear in my 1968 Firebird convertible. They are pretty pricey too, and hard to find, but regular 8.5" Firebird/Camaro 3:08 posi rear ends are plentiful. I got it to fit by cutting off the spring perches and re-welding them to fit the '68 body. The angle is only a few degrees different but it is enough to stress the leaf springs. I mounted the springs, fit the rear, spot welded the perches, and then took it apart and welded it properly. Can you weld? Have a welder friend? That is a plan. The only thing I don't like is the C-clip axle retainers. They make C-clip eliminator kits and that is nothing more than the old Pontiac type axle retainers like you have now. Worst case you have a GOOD welding shop do the welding. I know a guy in central New York, Seneca Falls. He is John Giovaninni, and he runs Gevo's Gears and Rears.Gevo's I have bought many used gear sets and carriers from him. Always very clean and useable. No junk. He has a Fleabay page too, lots of stuff. Gevo Ebay Look what he has right now: BOP 3:08 carrier And while I don't see any BOP gears sets, he may have them if you ask. Or get a Chevy gears set and just change the companion flange and U-joint to Chevy 25 spline style.Chevy 3:08 Lots of ways to get what you want. Last time I was at Gevo's he had a mountain of rear ends. I'm sure he can hook you up, maybe with a whole rear all ready to go.

Thanks for your thoughts. I had to call around a bit and luckily Phillips Muscle Car, which advertises in Smoke Signals, had a very clean set for $275. Just a tiny spot of flash rust (size of a dime) - everything else is sharp and clean. Can't wait to get see the difference.

I am glad you found some, they are getting scarce. Have you ever done a rear end? A lot of guys hear it is 'easy' and get in over their heads fast. I have a genuine GM pinion depth tool I grabbed at a swap meet. But that is not good enough. You need to read and understand the FSM to realize the concept. It took me many years [and some ruined gears] to finally get it.

I am OK with a wrench but the a rear gear swap is over my head. I am going to take it to someone reputable - that my be harder than finding the 3.08 in the first place!

It will be a nice increase in off the line performance, but be aware, the speedo is now going to be off and you will lose some top end speed.
All of which, can be remedied by some more $$$.

Jeff, Thanks for pointing that out. A few years ago I upgraded the front drum brakes to discs & bumped up from 14x6 to 15x7. So my speedometer and odometer are already off. I will be pulling the engine and tranny later this year to fix an oil pan gasket leak. I'll put the correct speedometer gear in place at that time.

While the tranny is out I am going to get a stall converter installed. Thinking something around 2200 will mate nicely with the new rear end gear ratio. Any stall recommendations?

Speedo gear changes: There is a formula to correct the speedo that uses gear teeth X mph which I never was able to make work correctly. I have a 1982 Buick Riviera FSM that actually has lots of pages that show trans, rear, tires, and what speedo gears belong together to get it correct. And even then I find I have to make a lot of speedo gear swaps until I get it right. I find the manual trans like Saginaw the easiest, since the inside output shaft gear never needs changing, just the speedo cable gear housing gears. I have a large selection of gears that cover a huge range. I also have the factory reduction gear adapter that they used for crazy rear gear ratios that fell out of the normal range of speedo gears. Automatics are a bit tougher because the gear housing is for a range of gears. You might need a different housing to use the right gear that you require. And even after all that, you take the vehicle up on the highway, have a buddy stay ahead of you with his modern car, and drive a steady 60 mph with the flashers on, check your speedo against that, and I bet you still won't be right on. But that's part of the fun.

You don't need to follow a buddy down the highway anymore now that GPS shows vehicle speed.

We tried doing that once and it was not as accurate. I even tried it on a boat while testing propellers and it was not even close. I guess for everyday purposes GPS will be OK, but here in Shitty City we have speed cameras on almost every block that use radar. Being off by even one or two MPH can get you a ticket. This gets problematic when you change tire size and it throws off your speedo by a small amount. The speed cameras are 'supposed' to give you a 5mph grace, but we have gotten tickets for being 2mph over. I blame speedo error.

I have installed many digital dashboards in cars and have used the GPS module for the speedometers and they are dead nuts accurate.
For the standard speedometer set up if you cant find the correct speedometer driven and drive gears they make an adapter that goes in between the transmission and speedometer that you can calibrate to the correct ratio.

Chief what do you compare the speedo against to know it is accurate? This is from GPS.gov: How accurate is GPS for speed measurement?

As with positioning, the speed accuracy of GPS depends on many factors.

The government provides the GPS signal in space with a global average user range rate error (URRE) of ?0.006 m/sec over any 3-second interval, with 95% probability.

This measure must be combined with other factors outside the government's control, including satellite geometry, signal blockage, atmospheric conditions, and receiver design features/quality, to calculate a particular receiver's speed accuracy.

Drive alongside modern vehicle going say 40 MPH and set calibrations for the digital dash to match 40 MPH.
I have done this many many times. Its accurate

So you still need an accurate modern vehicle to compare against. That is why I suggested following a buddy doing 60mph and compare your speed to his. I have an enginerd cousin who works on radar. He says even though the GPS is way superior to what it used to be, you will still be off by 1 or 2mph. And you MUST maintain an even speed or it will be wrong. He is also old school and suggested using highway mile markers and a stop watch then do the math. [that is what we eventually used on the boat to determine the speed. We got 55 mph over a measured mile on the water] Another cousin in PA says the State Police will give you a speedometer test on rollers for a small fee. Then you will be as accurate as a State Trooper car. His bone stock Ford Fusion car was off by 4.5 mph at 70mph. That's a speed camera ticket in the mail. This same cousin has a 1969 Barracuda and they don't make gears or an adapter that can correct his 5:38 rear gears. He then did the math and put some white stripes on his tach to know when he was at 30 and 60 mph. Finally, I don't know if you guys have these in your states, but we have these courtesy radar set-ups usually near schools and stuff. They say "Speed limit XX- your speed is__" I use those whenever I can because they are also State certified to be accurate. I had a cop stop me to ask why I was driving past the school so many times. When I told him I was calibrating my speedometer he was so impressed he didn't give me a ticket for doing twice the posted limit.

I'm originally from Long Island and never was pulled over for going 2-3 MPH over the speed limit anywhere in NY.
They got rid of those speed cameras in AZ because they have been proven nothing more than a money grab.
I left NY in 2005 because i seen where it was heading, your guilty till proven innocent.

Well then you know that they are extremely lazy here. But if the cop is having a bad day and you in his crosshairs, you are done. If you are experienced with the LIE then you know that everyone goes 20mph over the speed limit all day long. It's just a fact of life. The State Police will roll right along with you and wait for someone to do something else stupid, like change lanes without signaling. Then you get yanked for that AND the speeding ticket. The NYC website claims you only get a ticket for being 10 mph over, but if you think you are OK but the speedo is off by a couple mph, ticket time.

Hi, just read your post, good info. Not sure if I need posi for my 400. Can you help me decide? Thanks

The only time you really 'NEED' a posi is if you are racing, or driving in sloppy weather like snow. I doubt anyone is driving a first gen in snow, but racing is understandable. The OP's 2:56 is a pretty lame gear ratio, and it is only good for top end highway speed. I had a 1980 Firebird with 2:56 and hated that ratio.The 301 had a four barrel Q-jet and it never worked well. I actually back-fitted a two barrel Dual-jet, and it ran much better. My favorite ratio is 3:23, good acceleration, not bad highway rpm's. 3:08 is next best, with an automatic. My buddy had a 1967 Firebird 400, T-400 trans, came with a 3:08 posi. A very nice combination with great top end.

Bottom line is- if you can get a posi rear reasonably cheap, and can handle swapping it in, go for it. But if it is costing a bundle, and a shop must do the work, probably not worth it.