I don't think so. Those chassis are completely different. I think you have to use a Checy diff. The mounting is different and the width will be different.

ok Thanks Carl how hard is it to find a possie that would work I guess is my next Question haha here we go again !!

As already pointed out, the '64 Bonneville is a very different car compared to a '64CS. All you have to do is go on the internet and search some pictures of a '64 Bonneville and then do the same for a '64 Canadian model. The Bonneville has a wider rear end which, in my opinion, does a much better job of filling in the rear wheel wells compared to a Canadian model. (I could be wrong, but was the '64 Bonneville not advertised as a wide track Pontiac?) I am in the process of changing the offset/spacing on some 14 inch rims for my '64 CS. I have always disliked the enormous gap between the 225/14" tires and the inside lip of the wheel well. I firmly believe that these old boats should have come with 15 inch rims in the first place. I suspect that this is yet another oversight by GM. Since I am not prepared to change my mint '64 spinner hubcaps, I would likely have gone with different rims/tires 44 years ago when I purchased the car. I will post some pictures a little later when I have completed this project. By the way, one person who would know for certain is roger rabbit (Roger). In my opinion, he is unequivocally the most knowledgeable and talented member on this site.

Bill, it all depends on your bank account. New posi traction differentials run around $500.00 to $700.00.

If all I would have to do is pull the axles and change center section thats not bad at all..Brian can't wait to see what your going to do I too dislike the way the wheel well tire thing is like

Bill, there is no shortage of information on the internet. For example, type in the following on your search engine and see what you think. Sorry, but I could not make the link live.

www.classicchevy.com/assets/pdf/classicchevy/1955-64...

Is the center section of the 1964 Custom Sport the same as the 57 Chevy's? I can't remember how long Chevy used that center section, but I thought it lasted until the 10 & 12 bolts of 1965.

when it comes to rear gears ect I am clueless .?? number of splines ect no clue ,,to be honest haven't looked to see if its a 10 or 12 bolt.I have done alot of things on cars but .rearends and tranys I have always avoided

1955-1964 center pods or pumpkins are all interchangeable. The P or posi pumpkins are getting expensive as there are a couple on kijiji in the $1000 range. Over that time period a number of gear ratios are available.
3:08
3:36
3:55
3:70
4:10
4:56

The axles are different lengths so you cannot interchange axles from a 1962-64 into a 1955-57 housing because the axles are longer. The Posi pumpkins also use a shorter axle on one side.

There are pumpkins for sale and the prices vary depending on gear ratio and condition. I just pulled a set of 3:36 out of a 1963 that I am going to install in my 55 instead of the 3:70. I want to get the 261 to rev a little lower at highway speeds and try and get a little better gas mileage.

Al

It is easy. You just find an axle chart on the internet that will give you the correct length for a posi and take a good axle to a machine shop and get it cut to length. I would also recommend new axle bearings. The bearings need to be pressed on.

Al

I installed a posi in a 55 housing and I had to cut one axle appx 1/4 " to get it to fit. I can understand installing a non posi and using a shorter axle and it will fit and not be much of a difference and enough splines will mesh. I will be taking apart a posi from a 1956 housing in the near future and will measure both axles to check and compare with 55 non posi axles.

Al

If you want fully detailed info on 55-64 rears, go to the 58-60 and 61-64 forums on chevttalk and check for stickies at the top by DZAUTO, Tom is THE expert. Search his posts as well, he has detailed accurate info there with great pics.

He also tells you how to install an Eaton or Nitro posi in a Non posi case and compares them to the originals for differences. He also discusses axle lengths in detail.

He also has great posts on bellhousing and flywheel differences for Chevy transmissions.

If I remember correctly, the 55-57 (ish) had thinner gears so different axle lengths and were weaker than later rears. 55-62 vettes had the same rears as passenger and the rears are all interchangeable 55-64.