I'm seeking for any information (+ and -)on Columbia 2-speed Rear Axles which was available as an optional dealer installation in early Chevrolets.
Any information (technical; experiences on the road, parts sources) is highly appreciated!

Columbia two speed axles weren't for Chevrolets. Most of them were for Fords of the '30's and '40's. But they were used on other makes. Chevrolet overdrives were made by Truckstell. They were used in the torque tube behind the transmission rather than in the rear axle housing like the Columbia..Chevrolet's first overdrive was in '55. It was a Bendix unit and several suppliers are now making a kit with this unit. It's a kit to be used in the torque tube like the Truckstell. One of our members has a '41 with this kit installed and he's driven it across the country several times. It works well...The '41 is all stock otherwise...

For 37 Chevys, Two speed axles were available from Timken and Eaton. Two speed transfer case from Asam and Thornton. Of course Brown-Lipe and Watson made 3 & 4 speed intermediate transmissions. See web page < http://home.znet.com/t1937/4WD.htm > for details. .
. If your looking for better high speed travel and have a half ton, get a 3.36 rear end ring and pinion from Larry Jackson. If you have a passenger car, try to find Power Glide gears.

We have a 1938 Chevrolet Imperial (which is a 4-door with extended wheel base) standing in our work shop in Switzerland.
This Chevrolet was assembled by the General Motors Plant, Biel Switzerland.
It has a Columbia 2-speed rear axle (casting on diff.carrier is "COLUMBIA 2-SPEED").
The torque tube is assembled exactly the same way as on other original Chevy rear axles. Also the 2 transmission shaft bushings and the u-joint correspond to original 1938 Chevy parts.
The double row ball bearing (front of pinion) is hold in place with 3 screws like on all Chevrolets w/torque tube.
Both brake face plates and drums are original.
However, the axle shafts are not hold by C-clips but by retaining plates on the brake flanges.
The rear axle housing is one single piece from the left to the right brake flansh. (NOT like on the old Fords !!)
12 bolts hold the diff. carrier on the axle housing.
Maybe this Columbia 2-speed rear axle was only an option for Chevrolets assembled by GM Biel, Switzerland?!

I have a 38 coupe. I assume the gears you refer to would fit mine as well. I am NOT an expert on rearends. What year Power Glide gears should I look for & by gears do you mean the whole third member? Thanks.

The Power Glide gears will fit 1940-54 Chevrolet cars only.Same for the "third member"...

For 1937-39 Master DeLuxe cars the best bet is installing the ring gear and pinion or third member from a 1937-39 Master 85.That will bring you down from a 4.22 ratio to a 3.73 which will make a big improvement.If you already have Master (leaf front spring car) it has the 3.73.

These Columdia two speed diffs were also available in Australia as well. A friend of mine has two of them and about six or seven are known to exist. They were available only in 1937 and were used in Chevrolet advertising at the time.

It looks like I'm stuck then. I have a Master with the 3.73. I'm not really in a big hurry to get anywhere when I'm driving it. I just get a little paranoid on the 70 MPH freeway with everything going 70+ MPH to my 55-60 MPH. I feel uncomfortable running the old babbit beater any faster than that. Thanks for the help.

Tiny-The 3.55 gears would be a 5 percent improvement over the 3.73.That would be only a 3 MPH reduction at 60 MPH.Not really worth it.

I run my '39 at 65 MPH + with the 3.73s with no problem.The overdrive would be the only real help for maintaining a constant speed of over 70 MPH....and they will still continue to pass you on the Interstates. :(

Hi Fantir,
. The 127" Wheelbase Fisher bodied Imperial (Taxi, Limousine) used 3/4 ton axles in the USA with 4.11 (Rarely 3.83) ratio. In Europe, they could be gotten in Deluxe (4.22) or Standard (3.73).
. My Limo has two torque tubes, like the 3/4 ton trux.
. Could you email a JPEG of your Columbia?
. Thank you, Lou <c1937@znet.com>

Lou,
I'll be glad to mail you some pictures.
Our Columbia 2-speed rear axle has a 3.82 resp. 2.82 ratio.
It's for a light duty car and not for a 3/4 ton.