Hello Steve, I too also own a '97 Tahoe, and experienced a few minor
leaks over the years.
One, was a Heater Hose Clamp not even properly installed by the factory
near the firewall, two, was a leak at the underside of the Resevoir
Tank, noting the crappy little plastic Hose clamp on the line, I removed
tank, cleaned, inspected, and replaced with a decent Stainless Steel
Clamp, and three, the heater hose quick-connect on the top of the intake
manifold was always showing dried anti-freeze, so I knew this was a
problem, and decided not to replace with an original factory
quick-connect, but rather a 3/4" manifold-heater hose fitting available
from places like Auto-Zone-Checkers for just a few bucks.
Hope these suggestions may help you. Otherwise, as other posters have
mentioned, a pressure test of the entire coolant system will definitely
be the way to go. Usually places like Auto-Zone will do these checks