In 1968 or so I replaced the Fordo in my 55 312 bird with a T-85 o/d. The local junkyard (who's owner had an F code 57 bird) sold me the Dana 44 out of a 56 6 cylinder o/d wagon. Rear gear was 4.27 IIRC. I used 1.5 or 2" lowering blocks to get the car level. It came drum to drum, shoes were good, I just used it. Width was the same.
The 55 bird I bought in 1999 had the Dana 44. On going thru it the bird axle bearings wouldn't fit the axles. It was a truck Dana, bigger axles. It also had very crudely welded bird perches. Somewhere along the line the original 4:11 rear had been swapped out for a 4:11 truck rear end.
I've heard various explanations about Dana 41-45-? being variants. I don't know what's correct. I do know the birds, trucks, wagons and police cars usually had a Dana of some sort. All looked the same from casual looks from under the car.
They're getting hard to find parts for, at least the non 44 variants. If you're re going to change ratios, it's a pita. Having been thru it on the bird, I should have put a 9" or a newer 8.8 in
Randy's is local to me, they're pretty good with these. Various more modern vehicles used the 44 gears, including early Vipers.https://www.randysworldwide.com/
55 bird, 32 cabrio F code