The vin won't show a T or a GN, only if the the car is a factory turbo car or not. You will have to check the SPID on the trunk lid and see if it has the code for the GN. Which I can't seem to recall right now but I will locate for you. As far as the "Power 6" logos, the headrest and dash are very easy to change but a good starting point. Also, I believe only the GN came with black carpet, all others could only get grey.
Just found it, WE2 for '87