I have heard of other generation Celica owners using the stock 7th generation shifters as shortshifters. I sold mine to a guy, but I can not remeber if he had a sixth or fith generation Celica. I think it was a fifth.
By the way the shifter has nothing to do with how many gears you have. You can use a GT or a GTS shifter. I have GTS and he has a five gear Celica and it made no difference.