Opening a T5 Case for Internal Inspection
Inspecting the contents of a T5 case will give you plenty of good information. You can count the number of teeth on the gears, look for broken gears or parts, and see if things are in usable condition. This 31 photo slide show outlines the procedure I used to open my 1990 V8 Camaro T5 case. You will notice this T5 already has the S10 tail shaft housing swap done.