Turbo six logo on the center caps?

[groumoutis]

I have always wondered why they center cap turbo six logo is different that the rest of them on the car? Does anyone have to true without a doubt answer?

 

[ttaowner]

my guess is because the t type 86 and turbo t 87 center caps actually started off on the 84-85 gn and matched the horn cap is my theory