4cyl T5?

[Conman]

Ford rates the 2.3 t-5's at 240 ft-lbs
the 5.0 t-5's from 85-89 were rated at 265
the 5.0's from 90-93 were rated at 300 ft-lbs

for the 90-93's there was a higher nickel content in the gearset so the metal was actually stronger.

as for the 2.3's, I think they had the weaker alloy as well
Also a smaller shaft diameter would be weaker than the larger shaft although I don't think the shaft is the weakest part.
The higher gear ratio itself would also make the tranny weaker.
with the same input torque, the higher gear ratio would produce a higher output torque.

think about the gears in a rear end. It is alot easier to break the tires loose with 4.10's than it is with 2.73's, same thing with tranny gears except it's not just the tires breaking loose.