[mg man 75]

I know little on the standards. But got a website that may help. This is all off this site. More info maybe can find if look around. Trans Maybe.
Ford Transmissions
Casting number decoding.
Decoding Ford casting part numbers
I am pretty sure the a t-5 will not fit the 4speed bell. At least a t-9 and t-5 don't on the 2.3
Bellhousing info.
Bellhousings
Site I started off with to find what I found. Lot of info here.
Mustang tech and info links - Codes & castings
Maurice