Click on image for the lowdown. 
====
| | | Forums66 Topics128,115 Posts1,056,633 Members48,450 | | Most Online14,466
Apr 26th, 2026 | | AD Chevy Trucks  Over 6,000 pictures Brad Allen has an awesome collection of Chevrolet factory pictures that he has set up from film strips. Check them out!
Lots of work on Brad's part ... pure enjoyment (and references) for you!
| | THANKS!
For helping keep this great
old truck web site
on the Internet for over 30 years! and not clogged down
with Ads!  Again, thanks!
| | | | Joined: Feb 2002 Posts: 12,029 Cruising in the Passing Lane | | Cruising in the Passing Lane Joined: Feb 2002 Posts: 12,029 | looks to me like a TF rear - vent should be on top of the driver side toward the wheel, small "lump" that's a cover over a tube, which is threaded or pressed into the axle housing - they do get gummed up .... only change needed to swap in a Saginaw is a later fine splined yoke on the front of the drive shaft
Bill | | | | | Joined: Sep 2011 Posts: 814 'Bolter | | 'Bolter Joined: Sep 2011 Posts: 814 | OK, thanks Bill. I'll look for it in that spot. In the meantime, I pulled the cover off the differential. I don't see any damage and didn't find any shavings in the bottom of the pumpkin. All looks good. Someone has been in there, though, judging from the blue Permatex. [IMG] http://i7.photobucket.com/albums/y261/bohon/56%20Chevy%20truck/Differential065.jpg[/IMG] When I re-install the spacer, the manual calls for .014 clearance between the gears and the spacer on each side. I'm going to try for this but there doesn't seem to be any way to adjust if you're off. Or is there? I'm also going to try and post pics of the axle removal as I go. I figure it might help the next guy who's doing this for the first time.
1956 Chevy 3200
| | | | | Joined: Mar 2002 Posts: 9,115 'Bolter | | 'Bolter Joined: Mar 2002 Posts: 9,115 | Some spacers were made with two sets of ground faces. Turning the spacer 90 deg would then give a different size. You may want to try that. | | | | | Joined: Sep 2011 Posts: 814 'Bolter | | 'Bolter Joined: Sep 2011 Posts: 814 |
1956 Chevy 3200
| | | | | Joined: Aug 2011 Posts: 835 Shop Shark | | Shop Shark Joined: Aug 2011 Posts: 835 | Hey, great pics!
I bet the blue goo was someone's attempt to stop a leak....
Kurt | | | | | Joined: Sep 2011 Posts: 814 'Bolter | | 'Bolter Joined: Sep 2011 Posts: 814 | If so, it worked. But I'm going to put a real gasket on it.
1956 Chevy 3200
| | | | | Joined: Sep 2011 Posts: 814 'Bolter | | 'Bolter Joined: Sep 2011 Posts: 814 | So I found the vent on my rear axle but it appears the actual vent mechanism is missing. There is only a hole in the axle. I couldn't see it because it was covered with grime. I assume there ought to be some sort of device in there with a cap, etc. to keep out debris?
The other thing is there is some junk in the axle tube, all concentrated around the hole. I have an idea about cleaning it out but I wanted to ask if anyone else has dealt with this and has a good way to do it. I was going to stuff a rag soaked with lacquer thinner into the axle housing via the differential, then shove the rag through with a long rod from the other side. Then repeat the process for the other half of the housing. Does this make sense or is there a better way?
1956 Chevy 3200
| | | | | Joined: May 2012 Posts: 9 New Guy | | New Guy Joined: May 2012 Posts: 9 | Very useful posting, thank you for documenting what you've done and including pictures. This will come in handy later. Do you know if the axle in your truck is stock? I'm assuming the truck is a '56 Chevy 3200. I've been trying to determine if the rear end in my 55 1st was original and your pictures look identical to what's in my truck. From this forum I've learned that at least the 55 1st & 2nd used the same axle. My engine & tranny was swapped by a previous owner, a 350 & 400 Hydra from a '72 Camaro. I determined the gear ratio to be a 3.90 by turning the driveshaft just short of 2 rotations to turn the rear driver's side wheel once.
Someone else had posted the following on this forum.
"Can I put math in a sentence? (number of drive shaft revolutions) divided by (number of tire revolutions) times 2 would give the approximate gear ratio. If you have 4.11 gears expect to see the drive shaft turn just more than twice for each turn of the wheel.
If your gears are 3.90 you'll see just less than two turns of the drive shaft for each turn of the wheel"
Dan
55 Chevy 1st Series 1/2 Ton - 350/400 Hydra
| | | | | Joined: Sep 2011 Posts: 814 'Bolter | | 'Bolter Joined: Sep 2011 Posts: 814 | Yes, the truck is a 1956 3200. I had the same question--whether or not my rear axle was stock. I posted a photo here on the Stovebolt and I was told that it is in fact stock.
Regarding the math, I didn't know that was the way they arrived at the gear ratio.
1956 Chevy 3200
| | | | | Joined: Jul 2008 Posts: 413 Shop Shark | | Shop Shark Joined: Jul 2008 Posts: 413 | Another way would be to count the teeth on the ring gear and count the teeth on the pinion.
Divide the amount of teeth on the ring gear by the amount on the pinion, this will give you your exact ratio. | | | | | Joined: Dec 2003 Posts: 2,953 'Bolter | | 'Bolter Joined: Dec 2003 Posts: 2,953 | You should be able to find a brass fitting to fit in the hole on the axle housing. If you get one with a nipple you could run a piece of aquarium tubing from it and up to a point on the frame or even the axle. This will let the axle breath without losiong any gear oil. | | | | | Joined: Sep 2011 Posts: 814 'Bolter | | 'Bolter Joined: Sep 2011 Posts: 814 | I got one from Classic Chevy Parts. It's much like a PCV valve. So far, so good.
1956 Chevy 3200
| | |
|
|
