Is the 55,56 T bird differential a Dana 44?  Same as the 54-56 station wagon/courier differential.   

Yes, they're Dana 44's. There may be differences in bearing and axle sizes, I know the 44's in truck were different. There's also a difference in the spring pad height. When I put a 44 out of a wagon into a 'bird in the late 60's, I need lowering blocks to get the car back to level. IIRC, the brakes and parts all interchanged.

miker
55 bird, 32 cabrio F code
Kent, WA
Tucson, AZ

Dana 45s are third members in 55 and 56 T Birds.
Have never been able to ascertain all of the differences between the 44s and the 45s.
I know some of the parts interchange BUT not everything.

Oldmics

Here's a link to the various Dana 44-45 etc. The 45 was short lived. I can't vouch for the accuracy of this link.

http://en.m.wikipedia.org/wiki/Dana_44

Here's a link to a discussion here on 44-45's

http://forums.y-blocksforever.com/Topic81323.aspx

The rear end in my 55 is a 44, but when replacing the bearings I discovered it had the larger truck axles. That's what I was told when the stock bearings wouldn't fit, and I took the axle over to the parts store. Upon a closer look, the welding on the spring pads was pretty bad even for the day. I think a 4:11 truck rear end found its way into the car somewhere in the past. But I've had 3 gear sets and a posi unit in it, all 44 parts.

miker
55 bird, 32 cabrio F code
Kent, WA
Tucson, AZ

There is a 44 cast into my 55 Bird's housing.  Dont know much about the internals.

Don

thanks a lot for your input.  I have a 4:11 out of my wagon, will let it go cheap. Will post on the for sale side.