What transmission is in a 1998 K1500 Z71 with a 350 vortec?

It's a 4L80E, I have the same truck. The 4L60E was not in the "K" 1500

NEW ANSWER: Your truch has the 4L60E in it because it is a 1/2 ton. They put the 4L80E transmissions in the 3/4 tons and heaver trucks. NOT 1/2 TONS.