Just to confirm again, AT and XT use the exact same DIN shell. However, I believe the actual form of the plastic part differed between the AT and XT Model Fs. I don't know for sure but I believe XT is a metal housing and AT is the black plastic...but again, I don't know for sure.
Just checked my XT (dunno) and AT (1988) cables, identical connectors. Logo artifacts are nearly the same.
However, the cable itself is different. The AT cable is a bit thicker.
I'm not going to cut them to compare, but I'd say the AT cable is about 1mm thicker. It's easier to compare the coiled portion, as I can see the difference there, rather than having to feel it out.
Oh and the XT cable on my board is quite a bit shorter than the AT one.
XT:
Coiled portion: 1/2 as long
Coiled to Board: 1/2 as long
Coiled to DIN: 1/3 as long
Interesting.