When view from above, the rear signal housings are tapered where they mount to the rear cowl. The front signal housings are not tapered and extend further outward. The part numbers for rear signals are the same for K75, K100, and K1100; the front signal part numbers are the same for naked K75 and K100. The mounting pads are the same front and rear.
If your description is accurate, one of your rear turn signals is a front signal