I don't know all the EXACT details about the early one piece 4L60E vs. the later two piece 4L60E. My experience early vs. late 4L60E's has been for using an '0411 PCM on an early 4L60E. Long story...

There are many options. One challenge is the 1998 transmission, which might not work with the '7427 PCM (unless the 1998 Chevy 4x4 is manual trans).

dave w