No argument with Paul’s suggestion regarding moving to a ’57 or later rear axle assembly, CK.

I’m fuzzy on this, but my recollection is that there is SOMETHING about the ’57 station wagon and courier rear axle assembly that makes it the best choice for putting it under a 'Bird. Perhaps the location of the spring perches? Or, maybe it’s something to do with the brakes. I wish I was clear on this for you.

My recollection, also, is that the ’57 FoMoCo differential is NOT a true 9 inch. It is commonly referred to as a 9 inch, but to put an actual 9 inch into the ’57 housing, some grinding on the housing has to be done to get the pig in.

The spring perches or brakes on the ’58 and ’59 Ford wagons may be the same as the ’57… but I don’t know.

I wish I could remember where I read or heard what I’m trying to pass on to you here. I am sure about the installation of an actual 9 inch differential into a '57 housing. -I did it in '10 with a friend on a '57 'Bird. –My age is showing on the rest of it though.

Hope this helps. Maybe someone else can add to this.

NoShortcuts
a.k.a. Charlie Brown
near Syracuse, New York

Your best bet if you want a limited slip rear would be to go with a nine inch. OF course, the easiest one to use is a 57 TBird rear. Next in line would be any 57-59 nine inch which should be a direct replacement (Not sure of the spring pads on a 59). However, the original rears on a TBird had a lower spring mounting pad that was thicker than a sedan, so you would have to use a lowering block to maintain the stock height.

54 Victoria 312;  48 Ford Conv 302, 56 Bird 312
Forever Ford
Midland Park, NJ

Nope, not a dana 44. Some PO has apparently replaced with that during the cars lifetime.
My experience with updating older diffs is, it will be pricey IMHO to upgrade to a yet mediocre finish. I went thru a similar thing with my 55 bird. Final best solution was an all new rear end setup brake to brake. Choose your exact final gear, trac Lok version, and have it delivered, even get new brake options if you want.
FYI, the housing # on yours may be found on the right side of the back of the axle housing. A series of numbers. You can then go to your favorite diff. website and they should have a chart to ID what it is you have. Then start checking parts ad availability for that unit. good luck. Even if it were an original Dana 44 (Spicer), I found it wasn't worth the cost of upgading.

       A  L  A  N   F  R  A  K  E  S   ~  Tulsa, OK    

The '55 and '56 'Birds were Dana 44s, CK. The picture you've posted does not look like my recollection of what the '55 and '56 'Bird rear end looks like. Limited slip versions of the Dana 44s were used in a number of different applications, but I'm rusty on what.

Wikipedia has a lengthy write-up on the Dana 44 with input from several writers. I've pasted a piece of it below. Always double check Wikipedia info, but it's a start...

Scanning the Wiki write-up, it indicates that there have been numerous variations of the axle assembly to include:

- solid front AND rear axle, independent front AND rear suspension

- ring gear size (8.5 and some 8.9 inch)

- axle shaft diameters and spline counts

- pinion shaft diameters and spline counts

- gear ratios and two different carriers depending upon what gear ratio you're running

If you look at eBay, and do a search for ‘Dana 44 locker’,and then ‘Dana 44 limited slip’ you’ll get numerous listings of new units available that are:

- clutch type

- air operated (!)

- electro-magnetic (!)

These are offered by Detroit Locker, Eaton, Auburn Gear, USA Standard Gear , Aussie Locker, Spartan, ARB, and Yukon. Most of these appear to be for 30 spline Jeep applications, but I only did a cursory look.

From Wikipedia:

The Dana/Spicer Model 44 is an automotive axle manufactured by Dana Corp. and is used extensively among automobile manufacturers and in the automotive aftermarket area as well. The Dana 44 was first manufactured in the 1940s and is still being manufactured today, both front and rear axle variants. The Dana 44 has been manufactured as a beam axle and independent suspension for both front and rear axle setups. There are also different variations of the Dana 44. Over a dozen automobile manufacturers have made vehicles that feature Dana 44 axles, including Jeep which currently manufactures Four-wheel drive vehicles that feature both front and rear Dana 44 axles.

General specifications

• Ring Gear measures 8.5 inches (216 mm)
• Ring Gear measures 8.9 inches (226 mm)
• OEM Inner axle shaft spline counts are 10, 19, 29, 30, 32, 33 and 35
• Pinion shaft diameter: 1.375" (most Dana 44's) 1.625" (JK rear 8.9" Dana 44's)
• Pinion shaft splines and spline diameter: 26/1.12" (most Dana 44's post 1970), 24/1.25" (JK), 10/1.12" (early pre 1970 Dana 44's)
• Gear ratios range from 2.72:1 to 5.89:1
• Carrier break: 2.72:1 – 3.73:1 and 3.92 – 5.89:1.

On some differentials only the high speed 2.72–3.73 carrier is used for all gear sets up to 5.89 (JK, Nissan or when thick gears are used)
_________________________________

Hope this helps.

NoShortcuts
a.k.a. Charlie Brown
near Syracuse, New York

So its not a Dana 44.

My guess is '54 to '56 passenger car. Limited slips for those are nearly impossible to find.

John - "The Hoosier Hurricane"

I am looking into fitting a posi lock differential to my 55 TBird and looking at the centre it doesn't seem to be like the other Dana diffs.I know it is not a 9" as the pinion support does not separate, yet it is a Banjo style?
I see the Dana diffs have a salsbury style housing?

So I would like some help identifying my diff.
Please pardon the grease but here is a picture of it.