On the tail shaft of the transmission, there will be a stamped aluminum tag. The tag will have a number on it that you can cross reference to the chart below. There is no other way to find out what type of T5 it is without disassembling it. All the rest of the numbers on the outside of the T5 case are part numbers which are not unique to any particular T5 model.
Remember that 94 - 97 T5's have a longer input shaft and can only be used with a 94-95 bell housing unless you modify or replace the input shaft.
T5's used with a 4 cylinder have a 3.93 first gear, reduced torque ratings and an input shaft pilot diameter that is smaller that the T5 used for V6 & V8 engines. The Pilot diameter is .59" compared to the .668" used on V6 & V* T5's. It requires a different pilot bearing to be used with a V6 or V8. The pilot bearing you need is for a Ford Ranger diesel from AutoZone part #14672
Without going into to much detail as this is VERY easy to do...
1.) Get a fox length inputshaft from a V8 t5 from 93 or prior.
2.) Get the correct bearing retainer for a fox length input shaft again, 93 or prior. There is a shim behind the bearing race. Keep that.
3.) remove old bearing retainer by removing the 4 bolts that hold it to the case, smack it with a rubber mallet to losen it from the case, and pull off.
4.) line up the notch on the input shaft to the cluster gear so you can remove the inputshaft. A tip here would to be to invert the trans so the input shaft is facing the floor. There is needle bearings that are loose when the shaft is pulled and you dont want those in the trans... plus keep the orientation of the shim and bearings that you removed from the old input shaft.
5.) Move the needle bearings, and shims to the new input shaft. Also make sure you install a new bearing on the input shaft.
6.)place the shim you removed from the old retainer to the new one. using the new race you got with your new inputshaft bearing.
7.) install the inputshaft into the trans keeping the orientaton of the notch so it will line up and seat.
8.)install the bearing retainer, use a little sealant around the hole to prevent leaks. You should get the endplay checked, I never did, and I had no issues when I put a 94-95 trans in my car. But yours may be different.