Unfortunately, you cannot tell what ratio a T5 has by the engine in front of it. This is by far the most persistent myth. You can only tell by decoding the tag. Both ratios were available in front of a variety of engines.
A better rule of thumb would be year of application. 88-91 is almost certain to have the better ratio. Some '91 and all after that, however, have electronic speedo.
And realize these trannys are quite old now and given the interchangeability of parts, it's not uncommon for an entire gearset to be changed out, so, much like our beloved flatheads, you almost need to open it up to be sure beyond a reasonable doubt....
There is quite the collection of threads on the HAMB. Check the link in my signature...