There seems to have been an police or performance brake option for 1999 Tahoes. It also seems to have been used on diesel Tahoes (was there such as animal?) From what limited research I have been able to do most of the aftermarket parts suppliers (NAPA, Auto Zone, Advance Auto) list a standard and police option caliper, brake pad and master cylinder for the 99 Tahoe.
I am about to do some major brake work on my truck and if the calipers and master is all that was different I would consider the upgrade. Any insight on this option would be appreciated.

Police package most likely has larger diameter rotors, possibly thicker rotors. Calipers probably have larger pistons, so the brake lines could be larger. Just ask for all the parts for both and return the set you end up not using.

Unless you drive VERY fast or pull a huge trailer, there's probably no need for the upgrade.