I think any 7.3L will work for your transmission. Mine came out of an IDI. You can find a lot more information on my transmission thread. I recommend that you go with the 5 speed instead of the 6 speed because the 6 speed takes a whole lot more work to make it compatible, apparently.

 

X2 what Joseph said. Any 7.3 manual trans will bolt up, just need the clutch and flywheel for your year engine. The 96-97 ZF5-S47 is better than the 88-95 ZF5-S42.

And yes, the 6 speed will bolt up, but a lot more work to put it in.