4.56:1 to 4.11:1

Both 4.11 and 4.56 require the same "4 series" differential carrier.

Rick_L said:

Both 4.11 and 4.56 require the same "4 series" differential carrier.

Click to expand...

That is absolutely correct.
ANY 57-64 4.11 ring and pinion will fit your existing case as well as the posi unit.

And, just for added information, IF, just IF, you wanted to go with a 3-series ratio, then a 3-series posi unit would be required.

Postreaction! Spell check let me down again... Should read positraction.
OK, buying a 4.11:1 ring and pinion is easy, finding someone that can set it up without it howling is the hard part. As they say that is above my pay grade. As I recall I'll need to pull the axels out so it might be a good time to replace the bearings and seals, I'm assuming there are seals but they may have only gaskets. Any other suggestions?
Thanks... Al

Rear differential removal is covered in the Shop Manual: 1955 Chevrolet Passenger Car Shop Manual

Once you get it out. you are in the same boat as I would be

I did a bit of Googling and found these guys Xo-fab. 4x4 shops probably do more diffs than most shops.

They say they can do a good job.... " Extreme Options Fabrication is the name you can rely on when you want one of the best differential gear install services in the Federal Way, WA area. " 😁

I did a bit of Googling and found these guys Xo-fab. 4x4 shops probably do more diffs than most shops.

They say they can do a good job.... " Extreme Options Fabrication is the name you can rely on when you want one of the best differential gear install services in the Federal Way, WA area. "

Thanks for that, I'll check them out... Al

Just exchange the center to the new gear ratio