Metric Vs. non-Metric AX4N

[widlin1]

What is the difference between the metric and non-metric AX4N transmissions? and are they interchangable? I am considering looking for a used transmission for my 97 Taurus wagon and would like to know what will fit. Also I think i read once that all the AX4Ns are interchangable, but I also remember reading that some had a 5 inch vs a 3.5 inch bolt spacing on the top of the bel housing. Can some clear that up for me?

Thanks

Jeff