My 99 Tahoe is extremely difficult to change to any gear selection.
The first time I drove it, I thought I would break the lever.
Any ideas?

I would disconnect the lever at the transmission then see if the binding is in the transmission or if it is the shift lever/steering column.

//2000CAYukon

This problem was caused by a connecting cable from the selector to tranny.

It has been replaced and works fine now.

This problem was caused by a connecting cable from the selector to tranny.

It has been replaced and works fine now.
how is it that the cable was binding? rusted out or was the wire coating worn off.......

The coating was worn. This was a $333.00 fix at the tranny shop.